LONDON, July 19 (Reuters) - Britain recorded its highest ever temperature of 40 degrees Celsius on Tuesday (Jul 19) as a heatwave gripping Europe intensified, forcing train tracks to buckle and fuelling a spate of fires across London.

The Met Office said a new provisional record temperature of 40.3 degrees Celsius was recorded in Coningsby, in central England, with 29 sites across the country experiencing temperatures in excess of the previous high of 38.7 degrees Celsius recorded in 2019.

Stephen Belcher at the Met Office said he had not expected to see such temperatures in Britain in his career.

"Research conducted here at the Met Office has demonstrated that it's virtually impossible for the UK to experience 40 degrees Celsius in an undisrupted climate but climate change driven by greenhouse gases has made these extreme temperatures possible," he said.

Train routes from London up the east and west coast of the country were cancelled, electricity companies reported mass outages and normally busy city centres appeared quiet. Network Rail tweeted a number of pictures showing large bends and kinks in rail tracks.

London Fire Brigade declared a major incident and urged people to stop having barbecues, as 110 fire engines battled blazes across the capital.

To the east, a large fire engulfed homes in the village of Wennington, with flames tearing across neighbouring tinder-dry fields and approaching a historic church. Elsewhere large grass areas around the capital were on fire, blowing smoke over major roads and nearby areas.

Britain, which can struggle to maintain key transport services in extreme heat or snow, had been put on a state of national emergency over the unprecedented temperatures.