Fire Angel SB1 smoke alarm backing/ fixing plate (Malvern Link WR14)

A friend has recently had some decorating done and the backing plates to his 2 smoke alarms have gone missing, the alarms are still in date for another 4 years (a waste to bin them), SO an extremely long shot does anyone have 1 or 2 of these particular models lying around? perhaps just out of date and on their way to the bin or tip? Only the backing (fixing to the ceiling or wall) plates are needed but if you have the whole thing then I will recycle the main part. Thanks