@AlexDIreland@PaulJohnDykes wrote a great book on the Celtic jersey, he would be able to tell you specifics but believe Celtic wore Umbro uninterrupted from the 1930s through to the end of 04-05 season
@europerson@noonofday Believe the owner now owns the Seadog in Hastings, may be able to shed more light. May be the shirt of a pub/5 aside team (some free advertising in return for post match beers) - not uncommon in London