Awwww Paul, be nice to Julie, it was 6 years ago that she asked not recently
My update was recent which is why it popped back up again.
I should have also mentioned that my blue vase carries the RD number on the base as well.
I can't pin down the date closer as the Bagley Glass
book (Bowey, Parsons and Parsons) says Nov 1946, whilst the Nat. Archives catalogue just gives:
Reference: BT 52/2375
Held by: The National Archives, Kew
Legal status: Public Record(s)
Closure status: Open Document, Open Description
but unlike earlier entries there is no detail for the individual rd nos. - "not digitised" it says.
The only way to pin it closer would be to ask you to look it up on a future visit to the NA Paul, if thought necessary.