Phil,
Blue on bottom camou on top,
Tandem seat
Retractable undercarriage
You forgot to mention if it was a jet trainer or a prop job, I'm assuming the latter.
Unless the competittion for the Tucano replacement for the UKMTS entailed a fly off with say a Pilatus PC-21 and they decided a trial around the different bases such as Cranwell or Linton On Ouse and Wyton be needed.
Maybe Hawker Beechcraft decided to bring in one of their T-6A Texan IIs into the country and enter the UKMFTS and demo again?
Or was it someone's private aerobatic toy say a Yak 11?
I forgot about the Tucano's painted in Battle of Britain scheme as i saw a pair at RIAT 2010.