Noisy bird driving me crazy - would love to know why it's non stop (audio included)

Its driving me crazy, the same call of the same sound 4 times, every 6-10 seconds on repeat. It started on Monday and every day for several hours morning and afternoon it has been going on.

Come to think of it, I think I had the same thing this time last year for a number of weeks. 

I love birds and appreciate bird song (and that it's their home too) but this is driving me round the bend, quite piercing in volume and tone, bliss when it stops for a bit and then before you know it, he begins again. 

If anybody could help, Would love to know:

- What bird type it is,
- why it is doing it,
- how long it's likely to continue
- and is it likely to come back next year if it was here last year?

Here's the audio

www.dropbox.com/.../New Recording 2.m4a

Appreciate your help, off to buy some noise canceling headphones before I lose the will to live.