Your English summer weather is similar to what we get in Australia in the winter so my comment is totally irrelevant to most of you. We have had some disasterous fires caused by angle grinders cutting metal outdoors in the summer. One, two or three years ago, in the Perth Hills took out a number of homes.
Locally, during summer, I get phone messages from my shire warning of a total fire, harvest and hot work ban. A fire in February that came very close to us was caused by a spark from a ride on mower when the operator wasn't aware a ban was in place.
My workshop wood and metalwork area is shared so I do a big sweep up of shavings and saw dust before cutting or welding and also am aware of where the sparks are going so as not to speckle the window as Keith mentioned.
I usually stop hot work an hour or so before I close up shop to be sure nothing is going to light up after I've gone down to the house.
Cheers,
Geoff.