Its been annoying me since i saw the new advert for this is england. whats the name of the track in the background with the really cool ska trumbone?

Many thanks for your post - there are a number of different tracks on the promos for This is England, but hopefully this is the one you are after:
Music Title: Geno
Performer: Dexy's Midnight Runners
Writer: Rowland/Archer
Record label: EMI Records
Publisher: EMI Music Publishing

Thank you very much filmfour. Keep up the proper stirling work!