1939 Mk2 Clock Marked 13 MU

I received a nice 1939 RAF Mk2 8 Day Jaeger rim wind cockpit clock last week.

Interestingly it has 13 MU painted on the dial. Which I assume is 13 Maintenance Unit.

Am I correct to also assume that 13 MU at RAF Henlow had their own store of clocks that they used when testing/delivering aircraft?