The bird was ringed by Will Miles (of Leach's Petrel fame, if you subscribe to British Birds).
Will replied with the following interesting information on the bird:
"This is definitely one of mine, and the first ever record of one away from Kilda - totally brilliant! A live wintering at-sea record is particularly rare for these guys - so many thanks again. This fella is actually the second bird I ever ringed on Kilda. It is White/White (L) Red/White (R), ringed on Hirta on 22nd May 2007 as an adult (wing 441mm, weight 1510g, head&bill length 108.5mm). It nested every year on Kilda that I was there (2007-10) with only two other pairs on 'Mullach Sgar', quite a remote location away from the main colony in Glen Mor. Also, if I remember, the pair had rather a taste for Leach's Petrels too !"
"This is definitely one of mine, and the first ever record of one away from Kilda - totally brilliant! A live wintering at-sea record is particularly rare for these guys - so many thanks again. This fella is actually the second bird I ever ringed on Kilda. It is White/White (L) Red/White (R), ringed on Hirta on 22nd May 2007 as an adult (wing 441mm, weight 1510g, head&bill length 108.5mm). It nested every year on Kilda that I was there (2007-10) with only two other pairs on 'Mullach Sgar', quite a remote location away from the main colony in Glen Mor. Also, if I remember, the pair had rather a taste for Leach's Petrels too !"