RML45 Medium Shop and Office Block
This was basically two of the RML44 Small Shop and Office Block kits with a long name board
James Day has sent a note adding further information
The base unit was the same as supplied with RML 46 Medium Shop Office Block(Modern Style) , RML 37 Medium Shop and of course RML 68 Garage - Single Storey. The rear wall was different to the small shop RML 36 and the RML 44 Small Shop & Office Block as well, but as you say the other components were the same.
There are two colour variations for the brickwork portions of RML 44 & 45Dark as shown and the later Orange. Strangely the Town House RML 38, although sharing the same basic structure as the shop uppers was only ever issued with the later orange brickwork.