They may have been in search of the holy grail of the fourth chord for more than three decades, yet there's little doubting Status Quo's pure entertainment value.

The ever-popular grandees of rock have endured many twists of fate along the road - from early frilly-shirted flirtations with psychedelia to opening Live Aid and breaking the world record for most gigs in one day.

Radio One may have given up the ghost on playing their records, but that hasn’t stopped their army of fans from selling-out their shows.

For Quo bass player John "Rhino" Edwards it's been a rollercoaster ride and he has loved every minute of his eventful twenty year stint with the band.

"I always wanted to be in a really big band and never thought for a second that it wasn't going to work out. It's a great way to earn a living, it's far better than work," said Rhino, who joined when founder member Alan Lancaster quit after their famous Live Aid set.

It seems the Quo only know one way of operating and that's at full speed. Their world tours keep coming thick and fast and they have now produced more than 60 hit records since they started out in the early 1960s.

In recognition of their devotion to three-chord blues rock, they were not afraid to take a self-deprecating slant on their latest album title, In Search of the Fourth Chord.

The video for the single Beginning of The End saw them having a great laugh on the London Eye.

"We take what we do really seriously, but we don’t take ourselves serious," explained Rhino. "Filming the single was hilarious, it only took us an hour and a half to do. That was a brilliant day."

Having sold an incredible tally of more than 118 million albums, you can't help but wonder what more they have to prove. But what does Rhino think the secret to their longevity has been?

"Great songs with no pretensions," he says. "People come and see us and they know what they are going to get. They want to hear Rocking All Over the World, so we’ll play it.

"We get a great reception from our fans, who have stuck with us through thick and thin. Not all our records may have been great, but we are close with our audience."

Despite their immense success, there have of course been lows down the years. Notably, guitarist Rick Parfitt suffered a serious heart-failure and in true Spinal Tap style was nearly sidelined by a case of RSI from playing the same chords.

Then came the infamous ban by Radio 1, which deemed the denim-loving rockers too old for its audience. The band considered suing the Beeb back in the mid 90s over alleged ageism from the station’s producers.

"It did bother me at the time to be banned by Radio One, but to be honest with some of the rubbish they play on there I’m not surprised," said John. "I still listen to the station though and am a fan of Jo Whiley's."

His own experiences in the began as a teenager in Chiswick, South West London in the early 70s. From borrowing a bass to play in a low-key local outfit called Maniac Mouse he quickly developed a taste for the business.

He nearly scored a number one hit with an appearance with French group Space in 1977 on their track Magic Fly. "Elvis had quite a cheek to die then and keep us off the top spot. Not so long ago I backed an Elvis impersonator for a laugh," he quipped.

Afterwards, he enjoyed spells with Dexy’s Midnight Runners and playing alongside Fleetwood Mac’s Peter Green.

Before he was invited to join Quo, he says he had seen them several times before "They were not my favourite band (Free were the ones I followed, but Quo were really good. When they asked me to join I thought about it for two seconds and said yes!"

He’s played on more than a dozen albums with the band including their 80s classic In The Army Now. One thing for sure is that life in the group has been anything but dull with their legendary love of all-night partying.

"People often ask me just how fun it is being in the band- well it is a great laugh. But my favourite music moment was playing a gig with my two sons Max and Freddie which I loved.

Freddie has become a really good guitar player- he’s had Francis Rossi and Rick Parfitt as his teachers!"

In his spare time, he admits to having an unlikely hobby in caravanning. He’s also a dab hand at building work "I’m good with a sledgehammer" he chuckles. Is that where the nick-name Rhino comes from? "I won’t say on that’ I’m going to be the Austin Powers of music on that one and keep it for my myself.

Anonymity is something the 54 year-old has particularly cherished. He doesn’t get pointed at in the street like the group’s frontman, which he says would be a bit overwhelming. As he explains, their drummer Matt Letley is from Rochester and likethe rest of the group is keenly awaiting their return to the castle.

"It should be a really good one- last time we were there Francis caught up with a long lost cousin of his! I’m looking forward to it a lot- and can see why they call Kent the garden of England."

So long as their loyal fanbase continues to support them in the kind of huge numbers they have enjoyed, they’ll never be short of a stadium gig. Still possessing plenty of passion and energy for their live work, the Quo army marches on in style.

Status Quo play the Rochester Castle Concerts on Friday - tickets are sold out. The event is rounded off by the Castle Proms on Sunday.