WTE over Leamington Spa?

Pretty sure I just observed a WTE gliding over Leamington Spa. Quite high. Mobbed by a large gull.

Covered the entire line of sight without a single wing beat.

Definitely not a buzzard.or kite. Very very broad and wide wing profile and stubby neck. Absolutely enormous. 

Got the bins on it but it had glided too far to see any detail before I fetched them.

Gobsmaked. 

Could it be ?