The 25-year-old Chelsea Academy product has been loaned to Championship clubs for the past two seasons but had the misfortune to suffer a broken leg in November last year in a game for Leeds United, so returned to Chelsea after just two appearances for the Elland Road side.

In contrast, the previous season in Yorkshire when loaned to Sheffield United he gained plenty of experience and just missed out on the promotion play-offs, playing 33 times and keeping nine clean sheets.

Blackman is an FA Youth Cup winner with Chelsea and a former England Under-19 international.

He has also been on loan to Ostersunds in Norway and Wycombe Wanderers.