Sussex was recovering from its busiest weekend in 20 years today as experts predicted the heatwave would sizzle on.

Beaches, bars and hotels were bursting at the seams as a combination of tropical temperatures and the Pride festival transformed the coast into a magnet for thousands.

Paramedics, Coastguards and fire crews were run off their feet for 48 hours as the heat took its toll on sunbathers and dry foliage turned to tinder.

Isolated thunderstorms swept Sussex today as a huge clean-up operation continued to clear parched parks and litter-strewn beaches.

The exodus to the coast began early on Saturday as motorists fumed on the jammed A23 and travellers boiled in packed trains limited to 60mph because of fears tracks would buckle in the heat.

Rail passengers today described last night's return trip to the capital as a nightmare. Cancellations, delays and track closures led to hundreds clambering on to the overcrowded 11.02pm service which reached Victoria at 2.40am.

Police were called to protect South Central staff from disgruntled travellers. South Central spokesman Sam Hodder said today: "We would like to apologise to our passengers for the uncomfortable conditions.

"The combination of the unprecedented good weather and the Pride Festival meant there were many more people flocking to Brighton than we expected."

It was the hottest day in Britain since records began. The record was broken at Gravesend, Kent, with 38.1C (100.6F).

But coastal breezes kept the mercury down to a bearable 27C (81F) on Brighton beach.

The seafront was packed by 8am with latecomers struggling to find a place to lay their towels.

Across the city, businesses made bumper profits. Restaurants, clubs and pubs did a roaring trade with many enjoying record takings.

On Saturday night customers were queuing along the street for a table at seafood favourite The Regency, which seats almost 200.

Manager Roberto Savvides said: "It was a great weekend. With the weather and Pride we did very good business. It will easily be the most we have made all year."

Arun Patel, licensee of the Fortune of War, on Brighton seafront, said: "I would liken it to the Fatboy Slim concert. The levels of activity at 1.30am were just as high as earlier in the evening.

"We closed at 11pm but were still clearing up two hours later."

Maxine Silsby, duty manager at Alias Hotel Seattle at Brighton Marina, said the hotel was fully booked all weekend.

She said: "We've noticed many more people around the marina and our restaurants have done very well. It's been a lovely weekend and the atmosphere has been great."

Elsewhere, shops were running out of refreshments as thirsty punters raided shelves for drinks and ice creams.

Eddie Beer, owner of Seaside News on the seafront, said: "It's absolutely booming. We have been very, very busy all weekend.

"Unfortunately we ran out of ice and ice creams."

But Brighton Rock Shop owner Derek Burt complained: "Our shop down the road is booming but here we are losing money because the council has decided, in its wisdom, to dig the road up in the middle of summer."

As thousands flaked out on the beach or cooling off in the sea, some swimmers were leaping from the Palace Pier oblivious to the dangers.

Others sought shade beneath the pier.

Tony Ryall, 47, spending the day on the beach with his wife and three children, said: "It's a beautiful day. It's just far too hot in the glare of the sun. It's much cooler here and there is not much chance of getting burned."

Heavy delays were reported yesterday on the A23 northbound carriageway between Cheals roundabout and Ifield, near Crawley, as Londoners returned to the capital.

Roadworks between the A27 and Palace Pier caused severe congestion.

Brighton and Hove Bus and Coach Company apologised for delays caused by Pride but services were running more smoothly yesterday.

In Worthing, people were taking extreme measures to keep cool.

Temperatures soared on Goring beach as a group of game-for-a-laugh women peeled off their bikini tops while speeding along at 20mph on a jet ski.

Bank team leader Julie Anderson, 35, and administration assistant Helen Cross, 37, both from Worthing, raised a few eyebrows during their antics in the midday sun yesterday.

Helen said: "It was really exhilarating - a real laugh. The water was lovely and cooling. We got a fair bit of attention."

Earlier, their husbands David Anderson, 36, Paul Cross, 37, and friend David Crew, 38, had gone naked in the water - to cheers from sunbathers.

David Crew, from Lancing, said: "We just wanted to get our white bits brown. It was quite liberating."

The hot weather kept fire crews busy as dry grass acted as tinder.

A spokeswoman for West Sussex Fire Brigade said yesterday: "It could just be people being careless with cigarette ends and that sort of thing. It's just so dry at the moment, people have to be extra careful."

She said firefighters took 63 calls yesterday ranging from tree fires and a beach hut blaze to three field fires.

A spokesman for the seafront office in Brighton said: "It was extremely busy and extremely hot. There were lots of lost children, pier jumpers, drunks and other shenanigans which we had to deal with."

Supermarket chains also reported a weekend of record sales.

Tesco said disposable barbecues had been "flying off the shelves", while the store also sold record amounts of barbecue fuel and ice cream.

The food giants also said sales of lager, cider and alcopops were all up 45 per cent.

Eastbourne also attracted record crowds and one of the busiest weekends in memory.

Deckchairs had all been rented by 10am and there was hardly space to swing a bucket and spade on the stretch of beach between the pier and the Wish Tower.

With every hotel packed with guests, the tourism office has been ringing round guest houses in a desperate attempt to find beds for the influx of holidaymakers.

Seafront supervisor Garry Cairns said: "It has been brilliant. We have sold out of everything.

"The water temperature has been recorded at 21C (70F), which is hotter than it has been for four years."

Met Office statistics revealed the town had so far enjoyed more hours of August sunshine than anywhere else in England.

Ron Cussons, director of tourism at Eastbourne Borough Council, said last week's sunshine meant a boost to the local economy of up to £3 million.

Ben Booker, deputy general manager of the 152-room Grand Hotel in King Edwards Parade, said: "We have been full up all weekend. We are very happy hoteliers."

A family had a shock awakening when a thunderbolt blasted into the roof of their home today as isolated storms swept Sussex.

Colin Fullard, 31, and partner Dawn Williams, 30, were asleep when the lightning struck the house in Old Mead Road, Littlehampton, at 6.45am waking his three children Rhiannon, nine, Connah, six, and Megan, four.

Mr Fullard said: "There was this really loud bang, a smell of ozone and smoke, and I got the kids out of bed and out of the house.

"I had a look from the outside and there was a hole in the roof about the size of a basketball."