I didn't need to be particularly fast to get the shot, he/she wasn't going anywhere but I wanted to waste little time in getting the helpless creature out of it's plight. A couple of shots and I lifted the swift off the ground so it could take to the air again.
The bird wasn't injured, it had somehow misjudged the situation and landed on the ground. Their wings are so long, and their legs so short that they cannot take off from the ground. They eat, drink, sleep and mate on the wing, only landing to nest.
Swifts can fly up to 20,000 feet and a young swift can spend 2 or 3 years in the air without ever landing. They come to Britain as summer visitors from central and southern Africa each year.
I was glad I discovered the extended ISO setting for the dim evening light but I was sorry I'd just taken a landscape shot and left my camera on f/9, I could have used a wider aperture and not needed the grainer high ISO.