Allon joined Newcastle United in 1982 and made his debut in the first team when Jack Charlton was manager in a 2–1 win over Stoke City at St James' Park on 1 December 1984.
During the season, Allon also scored against rivals Cardiff City in the South Wales derby, in a 2–2 draw at Vetch Field on New Year's Day.
He scored 12 times in 40 league and cup appearances in a partnership with Colin Pascoe before he returned to the North-East to join Hartlepool United in November 1988 as one of Bobby Moncur's first signings as manager.
As Pools improved in the second half of the season and moved off bottom spot after being rooted there with 9 points from 18 games, Allon managed 17 goals in 45 league starts to become the club's joint top-scorer with strike partner Paul Baker.
Allon enjoyed a reunion with his former Newcastle United teammate Gascoigne in September 1990 as Pools played Tottenham Hotspur in the League Cup.
[3] His form in the 1990–91 season earned him a move to top-flight side Chelsea in August 1991, with manager Ian Porterfield paying a fee reported to be £375,000.
Allon scored at home on his Chelsea debut, at the Shed End, however, he failed to make an impact at Stamford Bridge after sustaining a leg injury which became infected.
[3] In February of the 1991–92 season he joined Port Vale on loan, but made just six goalless appearances for John Rudge's Valiants, who struggled in vain to avoid relegation out of the Second Division.
[3] He had a brief spell on loan at Southend United in September 1993, where he punched manager Barry Fry in the face upon scoring his 100th career league goal.
[8] Chairman Bill Bell arranged a deal to sign Allon on a free transfer, but Brentford would be paid £2,000 for every appearance and £1,000 for every goal he scored.
[1] He scored 11 goals in 34 games in 1996–97 to again become the club's top-scorer, as Hartlepool finished just four points above the bottom of the Football League under the stewardship of Mick Tait.