Lahiff was born in London and was educated at Papplewick School[1][non-primary source needed] in Ascot followed by Wellington College[2][non-primary source needed] Berkshire where he was a member of the team that won the Under 18 Daily Mail Cup.

[3][4] It was announced that he would leave Irish at the end of the 2012–13 season and link up with the Melbourne Rebels ahead of their 2014 Super Rugby campaign.

He also spent a season playing ITM Cup rugby in New Zealand for the Hawke's Bay Magpies.

[9] Rejoining Toby Booth and Neal Hatley, who were coaches at London Irish during his spell there, Lahiff was named in the squad to play Harlequins in the LV= Cup the next day.

[10] Lahiff signed for French Top 14 side Clermont as cover during the 2019 Rugby World Cup, but the deal was called off due to a medical issue.