Britain will bask in a mini Grand National heatwave with temperatures set to be hotter than Barcelona in parts of the UK. Sunshine and warm weather is expected to brighten the country today, with highs of 21C baking race-goers heading to Aintree; temperatures are likely to be a whole 10C higher than usual.

And thermometers will rocket even higher on Sunday, with maximum temperatures of 24C – the hottest day of the year so far – and constant sunshine.

But it may not be such good news for hay fever sufferers. The Met Office warns of a ‘high’ or ‘very high’ pollen count in London and the south, the midlands, Wales, Yorkshire and Humberside and Northern Ireland.