Mark 's trip to Spain to see Manchester City play Real Madrid on Tuesday has led to consternation from one fanbase over the former referee's judgement 24 years ago.
Halsey, who retired as a professional referee at the end of the 2012-13 season, travelled with his daughter Lucy and her Spanish boyfriend, who both live in Spain, to the Bernabeu for City's 1-1
But fans of League Two side Gillingham were not as cheery as others were to see Halsey enjoying a City match from the stands.
Gillingham faced City in the 1999 Second Division play-off final at Wembley Stadium with Halsey as the referee.
The Kent-based side were 2-0 up with 89 minutes played before City struck twice, the first from Kevin Horlock on 90 minutes and the second from Paul Dickov in the fifth minute of injury time, something Gillingham fans still feel was an injustice as City would go on to seal promotion via penalties.
Former Premier League referee Mark Halsey (left) went to support Manchester City against Real Madrid on Tuesday night with his daughter Lucy (right) and her Spanish boyfriend
Halsey shared a photo on Twitter of the trio and write 'come on City' as he headed to the match
Gillingham fans recall Halsey officiating their 1999 Second Division play-off final versus City
Halsey's revelation that he was supporting City on the night quickly reminded Gillingham fans, who do not seem to have forgotten Halsey's decisions 24 years ago.
'Actually joking. Knew he was a City fan. 99 is still fresh in my memory,' Toby Whitehead tweeted.
'After 24 years, it finally makes perfect sense #gills,' another fan added.
In jest, one Man City fan wrote: 'Hahahahhaha Halsey was the ref vs Gillingham in ‘99. Cheers for all the added time, Mark!!!'
Halsey, enjoying his family trip to Spain, largely ignored the fume from Gillingham fans but did reply to one remark that called for an 'FA investigation'.
'Get a life!!!!!!!' Halsey fired back.
Gillingham fans quickly took issue with Halsey and his trip to watch City as they remain angry at decisions from the game 24 years ago - but Halsey reminded people he is in fact a QPR fan
The tweet soon gathered even more momentum and Barry Ashby, one of Gillingham's starters in defence in that match, waded into the row.
'I quite like him to be honest, let me off a nice handball early on in the game, he asked me if I handled it as well, course not,' Ashby tweeted, complete with two laughing emojis.
Halsey, who is a self-confessed fan of Championship side QPR, responded: 'How are you pal I remember that handball I gave you the benefit of the doubt.'
In reply to another poster asking why he was following City as a QPR fan, he replied: 'Absolutely, but got to support English teams in Europe.'