The 22-year-old goalkeeper only joined The Lions on a permanent deal in the summer following his release by Tottenham Hotspur.
Archer come through the academy system at Spurs but spent a lot of his time gaining experience on loan with the likes of Bishop's Stortford, Wycombe Wanderers and Northampton Town.
He did make the Spurs first-team squad and was on the bench for their game with Swansea in 2013 – but he was again sent out on-loan, joining Millwall earlier this year.
He made the move to The Den permanent in the summer and wasted little time in becoming first-choice under Neil Harris – but already his form has attracted the attention of a host of scouts from the Premier League and Championship.
It is understood that Everton, Swansea City and Southampton have all scouted Archer on more than one occasion and are now considering making a move for the Scottish Under-21 international.