I realise that it is many years since this post was active but having only recently discovered it I felt the need to respond, partly in the hope that the original contributors are still with us, but also that the subject of George Clarke Motors should be extended since I was active with the company in the early 1960's.
The original post details the existence of the showroom in Brixton Hill and the Spares Dept on New Park Road, close by, but does anyone remember, or even knew of, the Bike storage facility somewhere in the back streets close by the Spares Dept ?
This was a substantial warehouse behind local terraced houses, accessed through a gated tunnel and a small court-yard with a wooden office/shed.
New and second-hand motorcycles sold from the showroom and bought on hire purchase were shipped to and stored in the warehouse until the buyers finances were completed. The new owner would then be issued with a docket, pink in colour I seem to remember, which he, or she, would present at the warehouse to collect their machine, which we would furnish with a quart of petrol and level checked engine oil, as required.
I feel this will do as an introduction and I will offer more if there is any further interest.