As a retrospective article from a Brighton v Rotherham programme from 1994/95 put it:
Few Albion fans believed it when, in July 1986, Alan Mullery starting his second stint as manager, announced that he would have two World Cup players in his Second Division side about to start the new season.
Just in case you thought he was going all out to revive the mothballed Juan Carlos Oblitas and Percy Rojas deal from 1979, the result was less exotic. Northern Ireland winger Steve Penney was already a Brighton player, of course. Then, Mullery’s next move was to sign Gerry Armstrong, Penney’s compatriot, who had famously scored the winner against hosts Spain in the 1982 World Cup:
By summer 1986, Armstrong was aged 32, having played for Bangor, Tottenham, Watford, Real Mallorca, West Bromwich Albion and Chesterfield. That he was in the twilight of his career was underlined by the fact that the Belfast-born centre-forward hardly set the Goldstone alight. He took until December to get on the scoresheet for the Seagulls. He broke his duck following in Darren Hughes’ blocked shot from close range against Leeds in a 3-1 defeat. Although he scored again in the next match, a 3-0 thumping of Shrewsbury, a writer for the Grimsby Town matchday programme was moved to state:
Rumbustrious Gerry Armstrong, the Northern Ireland World Cup hero, has failed to make an impression following his summer move from Chesterfield. Despite his international exploits, Gerry has never delivered the good consistently in the Football League. Earlier in his career he commanded a £250,000 price rage when moving to Watford, but arrived at the Goldstone on a ‘free.’
I don’t know whether Armstrong read this comment before the Brighton team left the dressing room for their match with the Mariners on Saturday 3rd January 1987. If he did, it might have fired him up. His winner at Blundell Park showed his ability to tidily convert a loose ball was still alive. After pressure from Dean Saunders, Armstrong capitalised after the ball had hit the woodwork. The sweet 2-1 result put clear blue water between 15th place Brighton and the relegation battlers. However, two days later, the man who had brought Armstrong to the Goldstone, Alan Mullery, was sacked.
Armstrong was then loaned to Millwall before returning to the Goldstone to coach the youth team, as well as taking the number nine shirt in a highly depleted Barry Lloyd-led Brighton side towards the end of 1986/87.