Britain's heatwave has sent ice cream sales soaring - and the warm weather is set to last with the country predicted to be hotter than Algiers, Budapest and Bucharest tomorrow.

Some ice cream vendors say they have had their busiest April ever as Britons cool down.

The balmy conditions will continue for another few days with the mercury predicted to soar to 17C (63F) on the Sussex coast as the Queen celebrates her 89th birthday tomorrow - making it hotter than Algiers, Budapest and Bucharest.

But the weather is then set to take a turn for the worse, with rain, cloud and cooler temperatures predicted for the second half of the week.

Forecasters said showers could hit the capital this Sunday as tens of thousands of runners take part in the London Marathon.

Ice cream vendor Katy Alston, 47, known as Mrs Whippy to her customers in the Sussex towns of Bognor Regis and Chichester, said the good weather has sent ice cream sales through the roof.

She said: "We have had a nice warm April and it has been absolutely amazing for sales.

"In April we usually potter around and find our feet, but this year it has been really busy. We did an event last week at Chichester University and sold out of ice creams in 40 minutes. It was just incredible - and it's down to the weather.

"Everybody says people eat ice cream all year round whatever the weather, but they don't. Children want to but adults won't let them.

"We have had our best April ever and I have been in business for 11 years. I would say our turnover for April has trebled."

Ms Alston, who runs the business with her daughter Georgia, 23, who is known as Little Miss Whippy, said the traditional 99s, and lemonade and cherry brandy ice lollies are her biggest sellers.

Dan Williams, a spokesman for the Met Office, said most of Britain has basked in sunshine today and will continue to enjoy good weather until Wednesday.

He said: "There has been lots of sunshine around and the temperatures have been pretty decent for this time of year - temperatures have hit 19C in Sussex and 18C in London.

"Generally speaking most places have had some decent sunshine.

"Tomorrow is a good day again in England and Wales, lots of blue skies and sunshine and temperatures in the high teens."

Patchy rain and breezier conditions are expected to hit at the weekend, and could bring unsettled conditions as runners line up for the London Marathon.

A spokesman for the Ice Cream Alliance, which represents UK sellers, said: "The hot weather has given ice cream sales a terrific start to the summer season.

"Some of our members have reported an increase in sales of ice creams and lollies of 400%, all due to the sunny weather."