Possible insect sound

[JTWH]

Hi all,

I have a puzzler for you. I live in Bedford and recently moved house. One night in the new house I noticed a strange beeping noise. Initially I thought it might be something like a smoke alarm with a dying battery, but on subsequent nights I have discovered that it is coming from outside and that I can hear a number of them in the neighbourhood.

I managed to track one of these beepers down to within a few feet. It seemed to be coming from within a small privet hedge, but I couldn't see the source and didn't want to spend too much time shining my torch around for fear of alarming the neighbours! I live on a Victorian terraced street, so fairly urban with small front gardens, although the houses back onto the River Ouse.

The beeping usually starts at dusk and seems to continue most of the night, although I think it may stop when it's cold.

I did manage to make a recording, which I have uploaded here. You can hear beeps from more distant beepers straight away, but the first beep from the one I got close to is at 38 seconds.

Any suggestions as to a possible ID would be greatly appreciated, or even a possible thought as to what to look for next time I go hunting for one.

Thanks in advance!