Winger returns after loan spell expires.The U's squad has been bolstered by the return to fitness in recent weeks of Sanchez Watt and Freddie Sears, whilst Gavin Massey is also making good progress.
The teenager made a total of four appearances (three starts, one sub) for the U's before his month loan concluded.
He grabbed the first goal in a 4-0 win over Stevenage on Boxing Day - the U's joint biggest victory on December 26th.
Blair originally signed until January 4th and, with no game for the U's this weekend, has now returned to his parent club.
Loanee winger Blair Turgott is to return to West Ham after the conclusion of his month long spell.