The day after Whitsun: the seventh Sunday after Easter, which celebrates the coming of the Holy Spirit in the form of flames to the Apostles.

In England this is normally the first bank holiday of the year where you have more than a 1 in 1*10^20 chance of decent weather.

Until recently this was the date of the Gloucestershire Cheese Race, and is an important day in the Morris Dancing calendar, but don't let that put you off.