My Dad has been trying to find his Dad's movements in the REME and was recently sent a copy of his tracer card. Specifically we are trying to establish where his Dad would have been around February 1944. The card has a line that seems to be "Holding Btn and SOS 21AG 17.2.44" What does that mean please? Is that likely to be near home (South Yorkshire)? If anyone can shed any light on where he'd be before and after that date we'd really appreciate it. Thank you.