I've had another look back at local stats to 1797 and reached the following conclusion on summer: average

"This summer is looking an average one. Before you write it off, however, average summers do come with decent spells of warmth and sunshine. But I think the old saying that an English summer consists of three fine days and a thunderstorm will be used more than once this year..."

Most likely 'hot' spells... June 28th - 30th and August 15th - 19th

https://wansteadmeteo.wordpress.com/...-2015-average/