Reports at the time suggest officers were despatched to keep an eye on up to 30 properties around the world, including in the US, Europe and Caribbean, where it was felt he could take refuge.

The Howletts mansion and ground had been owned, since the late 1950s, by John Aspinall - a man who had turned his back on a university education in pursuit of making his fortune in the world of gambling.

He had used money generated by his running of various betting establishments to fund the purchase of the sprawling estate and allow him to create his very own private zoo.

Cash had flowed in with gusto when, in 1962, he opened the Clermont Club in an 18th century, Grade I-listed building in Berkeley Square in London's Mayfair. An exclusive gambling venue which catered for those with ample money to fritter on the luck of the cards.

Legend has it that when the venue first opened its doors, its clientele list consisted of five dukes, five marquises, 20 earls and two cabinet members.

And among them was John Bingham - better known as Lord Lucan.

The two became good friends and formed part of a close-knit group who enjoyed the finer things in life – not to mention the thrill of a sizeable bet. They were the sort of band of men who would cover up each other's indiscretions; to protect one another at all costs.

Back in those heady days, neither man can have possibly imagined how their names would become entwined around one of their subsequent disappearances which has captivated the British public for almost 50 years.

Before events overtook them, the pair would brush shoulders at the card tables with the likes of James Bond author Ian Fleming, who had a house in St Margaret's Bay, near Dover, and comedy legend Peter Sellers.

It was through the success of the club that Aspinall could fund the purchase of Howletts, then a country house set in some 70 acres of countryside.

It was there he would indulge his love of animals and create a private zoo (something of an upgrade from keeping wild cats at his London pad). It has become his lasting legacy, having opened to the public in 1975, followed the year later, by its sister site Port Lympne, near Hythe.

But back in 1974 that legacy seemed a distant dream as officers hunted the outbuildings and grounds in the hope of locating the missing Lord Lucan.

The then-39-year-old had not been seen since the murder of his children's nanny, Sandra Rivett, and the attempted killing of his wife, Lady Lucan, in a bloody attack at his wife's home in Belgravia on November 7 - some nine days before the Howletts search took place.

The couple had become estranged with Lucan becoming increasingly obsessed about regaining the custody of his children. The blood of both women attacked was found in a car driven by Lord Lucan and found abandoned in Newhaven several days after the incident. His wife identified him as the assailant.

In a phone call to his mother after fleeing the scene, he claimed to have walked past his family home to witness his wife being attacked and had run to her rescue, before Lady Lucan accused him of hiring a hitman to try and kill her.

He is reported to have driven the Ford Corsair first to the family home of a friend, Susan Maxwell-Scott, in Uckfield, in East Sussex, a little over 15 miles from Tunbridge Wells. There he wrote two letters to friends (saying to one he was going to "lie doggo for a bit"), signing them 'Lucky' - the nickname he had earned after a 48-hour spell of gambling in 1960 had seen him win the equivalent of £600,000 - although his gambling subsequent to that had seen him build up heavy debts.

After leaving the Uckfield house, he was never seen again.

It was widely reported at the time that many thought he had boarded a cross-Channel ferry or a smaller vessel, in Newhaven and then gone overboard. No body has ever been found.

That disappearance has enthralled many.

Where could such a high profile peer go? Was he dead or alive? If he was in hiding, where was he? Who had helped him? Was he guilty or innocent?

More often than not, our fascination obscured the brutal murder of the 29-year-old Sandra Rivett, a young mother, which he had committed just prior.

In the last verdict of its kind, a coroner's court the following year declared him guilty by murder in his absence.

It had heard that Ms Rivett was not expected in the home at the time of the attack, and her death had been a case of mistaken identity by her husband, before, in his panic, he attempted to bludgeon his intended victim - Lady Lucan.

Convincing him he could spare her and escape, he left her, wounded on a bed for a moment before she seized her chance and ran to a nearby pub to raise the alarm.

A death certificate in his name was finally released in 2016. Yet his fate continues to baffle police. So why the connection to Howletts?

The day after Ms Rivett was killed, John Aspinall and a group of his closest confidants from the Clermont gathered at Aspinall's London home to discuss how they could help their friend during his time of need. Exactly what was discussed at this meeting will be forever unknown.

Speaking to the media in the week following the murder, Aspinall said: "I find it difficult to imagine him in Brazil or Haiti as a fugitive.

"I don’t think he has the capacity to adapt. He is a man of enormous virtue and honour. He could rely on many friends to help with advice."

Given their power and financial clout, many of the most popular theories suspect Lucan's friends helped mastermind his getaway.

And Aspinall lies at the heart of all of them.

Perhaps the most dramatic is a claim by Clermont regular Philippe Marcq.

Four years ago, he revealed fellow club member, Stephen Raphael, had confided in him that 'Lucky' Lucan had been secretly smuggled to Howletts by Aspinall and his chums.

Speaking to the Daily Mail, Mr Marcq said: "They told him: 'Look, it is absolutely terrible what happened. You are a murderer. You tried to kill your wife out of desperation for your children and so they would be free from her influence.

"But what you have done makes absolutely sure she will be in control of your children for years to come - you are a murderer and you are going to be in a cell for the next 30 years'.”

Aspinall and his confidants explained that he needed to vanish without a trace - a move which would delay probate on his estate for at least seven years - by which time his children would be old enough to handle their financial affairs.

Dismissing smuggling him out of the UK as he was "not cut out for a life on the run", a pistol was placed in front of Lucan. The fugitive, the story goes, then walked into the next room at the Kent mansion and shot himself.

His body was then fed to a tiger called Zorra.

It wasn't the first time the police had heard the theory. Possibly somewhat tongue-in-cheek, Lady Osborne - Aspinall's mother - had once told them: "The last I heard of him, he was being fed to the tigers at my son’s zoo."

When police visited Howletts, Aspinall is said to have responded: "My tigers are only fed the choicest cuts - do you really think they’re going to eat stringy old Lucky?"

However, according to a former secretary of Aspinall, Shirley Robey, the old Clermont gang knew far more than they ever let on.

She worked for one of Aspinall's casinos from 1979 to 1985 and claims she was privy to confidential meetings about the Lord's whereabouts.

Tasked with taking notes, she sat in on conversations between Aspinall and the billionaire James Goldsmith - one of the Clermont set - as they apparently discussed flying Lucan's two children to the Gabon in order for their father to see them, secretly, from a distance.

According to Ms Robey, Aspinall had told Goldsmith in the meeting: “It won’t be a problem. They won’t recognise him, he won’t make himself known to them, nobody will be aware of that.”

She added: "Mr Aspinall was pleased with it.”

Both Lady Lucan and her eldest son deny the trip to Africa ever took place.

Ms Robey added that Aspinall had also revealed a code which would reveal when the fugitive had died on the run.

She claimed that as long as Aspinall publicly stated Lucan was guilty of murder and had committed suicide immediately after the crime, she would know he was still alive.

She explained: "He told me that there would come a time when Lord Lucan would pass away and at that point he would give a message through the press and I would know that it was OK to speak."

In his final interview, before his death in 2000, Aspinall continued to maintain the same line - which Robey takes to believe that Lucan was still alive in 2000.

"He told me that there would come a time when Lord Lucan would pass away and at that point he would give a message." - Shirley Robey

She added: "He had certainly made it clear to me that he believed Lucan was innocent of whatever he was accused of. He just agreed wholeheartedly as did Sir James Goldsmith to stand by him and support him. I think he genuinely believed a mistake had been made, he was innocent, and he was doing the best he could to help him.”

Aspinall himself perhaps gave a little more away than he wanted in an interview to the Independent on Sunday in 1990 when he tantalisingly revealed of Lucan "I'm more of a friend of his after that [the murder] than I was", before quickly adding "though I haven't seen him - because if he wanted me to do something, I'd do it for him. Because he needs one and, like everyone else in life, I like to be needed. What's the use of a friend who, because you make one mistake, suddenly... I don't believe in that."

Another theory apparently sourced from those close to Aspinall and the Clermont set, came from the author Peter James.

He claimed they had arranged a private jet and flown Lucan to Switzerland where he was hidden in a chateau. But the plan unraveled when they became increasingly anxious their role in his disappearance could drag them all down with his increasing insistence he contact his children.

He claims he was told: "Aspinall and his friends panicked and thought they were done for. They had him bumped off in Switzerland, Mafia-style, and the body buried.”

In 2003, a book was published which suggested Lucan had lived out his final years in Goa and had been using the name Jungle Barry. This, however, was dispelled as nonsense by friends of the man pictured who claimed he was, in fact, a former busker from Lancashire, Barry Halpin, who left the UK in the 1970s to "hit the hippy trail".

And as if to demonstrate the Lord Lucan story continues to fascinate all these years later, the son of the murdered Sandra Rivett earlier this year sensationally claimed he had finally uncovered evidence to point to Lucan living in Australia.

Apparently now 85, Neil Berriman says he has tracked Lucan down and that he now lives as a Buddhist and is currently housebound as he awaits a major operation.

He says it was just one of "six" identities the fugitive has assumed since disappearing all those years ago.

Mr Berriman, who was adopted following his mother's death and only discovered his true identity in 2008, told a national newspaper: "Lucan is a deceitful conman and he is the man who murdered my mother.

"Lucan is a deceitful conman and he is the man who murdered my mother." - son of Sandra Rivett

“There is absolutely no doubt in my mind he escaped that night, with the help of friends who helped him get across the Channel and get a new passport, and incredibly he is still alive.

"He has been alive all this time. Lying about who he is. Lying about it to his new friends.

“They are fully aware he is a mysterious elderly Englishman and not who he is claiming to be."

The Met Police, who insist the case remains 'open', say they are following up on the claims.

Lady Lucan, who survived the attack, died after taking a “cocktail of drink and drugs” three years ago at the home where she had survived the attack from her husband. She had convinced herself she was suffering from Parkinson’s Disease. She was 80.

George Bingham, the killer’s eldest son, is now 52. He says he remains “very sceptical” about the latest claims his father was found in Australia.

Adding: “My father has been found many times over the years only to be wrong.”

The reality, of course, is that there is every chance we will never know the truth of what happened to Lord Lucan after that last sighting in Uckfield in November 1974.

And potentially the only man who could have provided the answers is now buried within the grounds of Howletts - within sight of the magnificent mansion which sits at the heart of what has now become one of the county's premier attractions.

John Aspinall’s passing in 2000 after suffering from cancer, at the age of 74, may prove to be the final resting place of the only man thought to be able to shed any light on the mystery.

But, then again, perhaps it is simply as Aspinall himself described it: "Lucan was very skilled at motor-boat racing, and I think he had a boat there at Newhaven, where his car was found, and I think he jumped into one of his little motor boats, went out to sea, put a big weight round his body and jumped overboard. And scuttled the boat. That's what happened."

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