'40 Patt BD RASC puzzle ?

1944 dated 1940 Patt. Battledress Blouse, Size 10 - 5ft 9"-5ft 10" Height, Chest 36"- 37", Waist 31"- 32" with clear manufacturer's label, size and inspection stampings. That it is the easy part.. to both sleeves, British troops Berlin designation, R.A.S.C. arm of service strip and the designation usually worn by City of London A.T.S. units. Printed war service chevrons to r/h sleeves. With the size of the tunic and the lack of any significant alteration it would appear that this was worn by a man and there are no obvious record of any use of the London designation by any other unit, this BD poses a puzzle, unless anyone knows different ? London TA unit ? RASC previous ATS attachment ?
Tunic in excellent, used condition with a 1mm hole to l/h breast pocket with slightly stained collar.

Code: 6678