Unknown Birdsong, County Antrim

Wondering if anyone can help ID this birdsong? Sounds like laser beams and it's always the same noise. I live near a river and woods in County Antrim, Ireland which is close to the coast. The closest thing I can guess is a greenfinch or even a song thrush but the thing putting me off both is Greenfinch is usually faster and a song thrush usually varies it's phrases. It''s this same song over and over.

Thanks

Gareth