What was the key ingredient that put our leading seaside towns on the map? Fishing? Industry? No. For the most part, it was, and brace yourselves, courtesy of the good folk of London.

Because while today there is a frequent refrain about how the focus of so many coastal towns is on the tourist from the capital, the reality is that was the very rock on which their foundations were built.

Which may make you think twice when you next complain about the ’DfLs’.

It would be wrong to suggest there wasn’t industry before tourism. There was shipbuilding in some, fishing in others.

But they were more coastal settlements than vibrant destinations.

That, however, changed in the 18th century when medical experts of the day declared that a secret weapon in the fight against a number of conditions was the healing power of the sea and the coastline’s bracing fresh air.

Dr Richard Russell was instrumental in extolling the virtues of submersing yourself in saltwater and, indeed, drinking it, to ease a casebook of ailments. Probably not to be recommended today, though.

The idea quickly caught on, and was particularly popular among the upper classes - which extended to King George III joining in - who saw such treatment as a golden ticket to a better life.

All of which sparked interest in travelling to places relatively close to London - remember, this was a time before both the car and train.

And one of the earliest towns to seize on the opportunities this created was Margate. It quickly introduced bathing machines - wooden, walled carts which could be wheeled into the waters for ladies to protect their modesty but take in some of that apparently life-enhancing brine.

It also opened, in the final years of the 18th century, what is thought to be the first sea bathing hospital in the country. Initially designed to treat the poor of London suffering from tuberculosis, it delivered a diet of fresh, sea air and recuperation.

English Heritage explains: “Margate has an important place in the story of seaside holidays. It is one of England’s earliest seaside resorts and it was the first to offer its visitors fully developed bathing machines with modesty hoods during the 1750s.

“As a result of its location along the Thames from London, it became the first popular resort frequented by middle and lower-middle-class holidaymakers.”

The result was that Margate’s prosperity started to blossom.

But things were set to change and open up other seaside towns in the county to cash in on this new-fangled tourism industry.

Was it piers? Theatres? Fairgrounds?

Well, they would all come, but before that it was good old-fashioned transport links.

Wind the clock back 150-200 years and the car was not an option. Instead, if you wanted to travel a decent distance in relative comfort then you needed a train - or a boat.

And for many of Kent’s towns, it was the boat which was the catalyst for change.

Paddle steamers emerged in the early 19th century and would take those living in London down the Thames, along the estuary and down the north Kent coast.

Londoners, perhaps not surprisingly, leapt at the chance to escape the grime, to see a different part of the country and breathe in some fresh air.

For Kent, those towns which saw its potential were the ones to benefit. And it was those closest to the capital which benefitted first.

“It was the beginning of the golden era Gravesend had in the early part of the 19th century at bringing in tourists,” explains Christoph Bull, a local historian.

“Coming down to Gravesend could be achieved in a convenient length of time - you could get there within a couple of hours from London.

“Of course, once the first few operators had success, many more joined and passengers had a huge choice.”

And with choice came more destinations.

Piers were hastily extended and reinforced in order to allow passengers on the boats to disembark – either for just a few hours or a matter of days.

Chatham and Sheerness (both of which had become a thriving hub of industry with the dockyards), Whitstable, Herne Bay, Margate, Ramsgate and Deal were all on a route which was extended as the demand grew.

It put the towns on the map and provided a vital summer season income boost which the locals were only too keen to benefit from. Make no mistake, the service was laid on for Londoners - offering them a passage up and down the coast, complete with on-board entertainment. They could catch the boat, at somewhere like Tower Pier, and be in Margate around four hours later. Once arrived, they had the option of either spending a few hours - and their money - in the town and then catching a return boat back, or staying overnight, fuelling the guesthouse business in the process.

Unsurprisingly, the likes of Margate particularly benefitted from the latter given the distance travelled.

At one stage in the 19th century, it was estimated the majority of Margate’s visitors arrived on its shores by boat rather than any other means of transport.

Sheerness emerged from the shadow of its dockyard and became a popular stop-off for those keen to explore its beaches but not stray too far along the coast. After all, the earlier you got off the boat, the longer you got to stay before your return vessel was picking you up.

But that too was about to come up against a rival which would prove the game changer - the extension of rail links to our coastal towns.

English Heritage adds: “Until the mid-19th century, Margate was at the forefront of the discovery of the seaside, but with the arrival of railways, visitors who had been restricted to travelling along the Thames could now explore stretches of coast further afield.”

Two railway companies started laying track to the far reaches of the county - South Eastern Railway (SER) and the London, Chatham and Dover Railway (LCDR).

The impact of their arrival cannot be underestimated. It opened up the potential of the port towns Folkestone and Dover - and extended the London holidaymaker’s reach. Suddenly, not only could they spend a few days of rest and recuperation on the south east coast, but even the Continent was within their grasp - if they could afford it. But for the majority, visiting our emerging seaside towns was exciting enough. By the mid-19th century, Kent’s popularity boomed.

Folkestone’s harbour was incorporated into the railway link and the town’s popularity soared. To give an indication of the impact of the railway’s arrival and the tourism industry it sparked, before it opened in the early part of the 19th century, the town’s population was, according to the Folkestone and District Local History Society, a little over 3,500. Within 50 years, it ballooned to close to 19,000 - an increase in excess of 500%.

It sparked a flurry of building. Large, grand hotels started being erected along its cliff top to serve the increasing number of visitors. Like Margate and the other towns before it, those Londoners were feeding the local economy.

Ramsgate Harbour station dropped people off literally by the beach, the trains emerging where, today, the Ramsgate Tunnels visitor attraction is sited.

They didn’t completely kill off the paddle steamers, but they proved mighty competition.

In Ramsgate, the Granville Hotel took full advantage of the opportunities, offering a direct special rail service daily from Charing Cross. The Granville Express sold itself on taking those from London to the Kent coast in just two hours. Legend has it, the hotel even built a ‘secret’ staircase in the cliffs to ferry hotel guests directly from the station to its cliff-top location.

In Margate, while many visited and stayed in the town, those with a few more pounds in their pocket were instead marketed the grandeur and exclusivity of Cliftonville.

As local historian Nick Evans describes: “Class-conscious Victorians thrilled at the chance of leaving the grimy city for lungfuls of healthy sea air, but to say you had spent your holiday in downmarket Margate was too much to bear.

“Instead, just a mile or so up the road from this brash, cockney-influenced fleshpot was developed Cliftonville – its cheek-by-jowl, but far better behaved, neighbour.”

Likewise, Broadstairs developed a reputation as being a relatively remote retreat for the Londoner with deep pockets and a desire for privacy. Its population doubled over a 50-year period of the 19th century.

In short, towns were transformed by the desire to cater for the London hordes. Regardless of their class, they brought with them money, and money, as they say, makes the world go round.

As the 20th century dawned, our coastal towns had never had it so good. While very much seasonal, the money they generated over the summer months comfortably catered for the remainder of the year.

In fact, in order to try and whip up the crowds during the off-season, the likes of the Winter Gardens in Margate was born - its name pointing to its purpose; events in a covered, heated building capable of producing entertainment year-round.

All the benefitting towns saw expansion - much of which is still noticeable today. The narrow streets around harbours tending to be the original settlement, before the wealth of tourism allowed it to expand outwards.

But the good times were numbered. The Great War put everything on hold. Folkestone became the town synonymous with the departure of troops heading to the killing fields of France and Belgium.

While things recovered during the post-war period, the Second World War changed everything again, German bombs ditched as they returned from bombing raids over London caused extensive damage. Defences against the threat of invasion saw coastal areas ringed with barbed wire rather than donkey rides.

As peace returned, slowly but surely, the industry found its feet again, trying to adjust to the changing demands of the population.

But what transport innovation gave with one hand, it would ultimately take away with another.

While Kent’s clement weather and proximity to London proved a key selling point, in 1950 the first affordable holiday package deals started arriving. Initially using surplus aircraft used during the war, they jetted people away to guaranteed sun.

By the mid-1950s they were gaining popularity. Why risk a rainy week in Folkestone if you could be enjoying the Spanish sunshine along with cheap food and drink instead?

For Kent seaside towns, the pinch began to be felt in the 1960s. Yes, they were still hugely popular, but where once they commanded an audience, cheap foreign jaunts and the widespread uptake of the car meant people had more freedom. In short, they could go elsewhere.

English Heritage adds: “The prosperity of the seaside continued until the 1960s, but with growing leisure time, increased disposable income and easy access to foreign holidays, all seaside resorts suffered decline, though none suffered as much as Margate.”

It’s not hard to see if you have all your eggs in a basket marked ‘London holidaymakers’, the loss of a sizeable chunk of that trade will have repercussions. Especially if those with deeper pockets opt out altogether. Hotels and guesthouses struggle to make ends meet, shops feel the loss of income; the whole financial infrastructure upon which they were build suddenly comes under strain.

Unemployment suddenly rears its head - especially among those relatively low-paid workers who relied upon a steady flow of tourists. With no other industry to employ them, it becomes a long-term problem. Young workers opt to seek their fortune elsewhere. The exodus fuels a drop in house prices, rents drop, income into local authorities takes a dip.

Once significant and prosperous buildings fell empty and into disrepair. Piers became ornamental rather than the conduit between tourists and places for them to spend their money. Lidos closed, amusement parks struggled. Theatres saw declines.

But perhaps most significantly, there was a loss of identity. Where once there was a pride in the flourishing tourism industry which put them on the map, the decline robbed communities of their raison d’etre.

The tourism legacy continued, but at a fraction of the level it once commanded. Memories of happy childhoods spent kept a trickle of visitors coming - but not enough to support the scale of the towns which had grown up to support it.

It would take decades for their fortunes to be revived once more.