This is from the 2010 RBBP report,
British Birds Vol.105 (2012), p 388:
.
Black-tailed Godwit Limosa limosa
Rare:5-yr mean 66 bp Coverage:near-complete
16 sites: 57–67 pairs.The numbers of nominate limosa remain steady,with the majority breeding
at the Ouse Washes. The number of confirmed breeding pairs of L. l. islandica (five), however, is
lower than it has been since 2005.
L.l.limosa 52–59 pairs
England, SW
One site: one pair bred, but is believed to have failed at the egg or small chick stage.
England, SE
Kent Three sites: (1) one pair bred,raising one young, one pair probably bred and two pairs possibly bred;
(2) one pair probably bred, but no more than display and copulation seen;(3) one pair probably bred, based
on agitated behaviour in mid July.
England,E
Cambridgeshire One site: 44 pairs bred and a total of 25 young fledged. Norfolk One site: four pairs bred, at
least two broods of fledged young seen. Suffolk One extensive site: a single displaying male, present for the
thirteenth consecutive spring,was seen at three coastal locations.
England,N
Lancashire & N Merseyside One site: one pair probably bred. Two males and a female were again seen displaying early in the season but no nesting took place. Yorkshire Two sites
1) one pair bred. Four eggs were
laid but lost to a predator;(2) one pair bred.A female with four newly hatched chickswasseen on 21st May.
A male, caught and ringed on 29th Aprilwas of the race islandica (ID supported by biometrics), but it is not
certain that the breeding pairwas of this race.
So my facts were a bit off but islandica certainly do breed in the UK