Just something which may I hope help here.
There is no official colour British Racing Green.
The colour was allocated to England under the international racing coloiurs scheme but each manufacturer was left to decide for themselves the actual colour for BRG.
Thus a Jaguar racing in BRG would be a different colour from say an Aston Martin BRG which in turn would be different from say Bentley BRG and Lotus BRG.
Normally BRG is taken to mean a very dark "emerald" green.
Keep in minad also the paint makers had their mix for BRG and a BRG from Dulux would be a different BRG shade to that from another supplier.
As an aside red went to Italy , Silver to Germany, French Blue to France , White to USA and so on. Some makers also had an extra identifying colour painted prominently on the car. BRM had a red nose band. Brabham had a gold noseband etc.
This was well before the sponsors dollars added their colour and liveries.
Cheers , Pete.