Strictly speaking Grand Central didn't "take" the 221s from AWC.
AWC handed back 221142 and 22143 to the rosco, and they sat on Central Rivers for several months receiving the same maintenance schedule as those in the active AWC fleet. IIRC the pair sat at Central Rivers all Spring, Summer and the first part of Autumn before ROG used class 37s to drag each to Worksop. The pair then sat unloved in the yard for a few months before the 37s dragged them back to Central Rivers for repairs to wheelset damage and exams to get them back into service.
AIUI the units are popular with the GCR Bradford crews and seem to be well behaved, but there is a problem !!! As only the West Riding GCR crew are competent on the 221s they can only operate the Bradford diagrams, and that means swapping the Sunderland diagrammed 180s at Kings Cross, to get them to their home depot at Crofton is not so easy.