£55 was quite a lot of money in 1952 for a second hand motorcycle, the British government were paying Norton £67 8s 4d in 1945 for the last batch of 16Hs. But you hear of people paying only a few pounds for bikes at Military auctions and sometimes even getting some free in the back of a lorry so this sounds like profiteering.
Surplus bikes were auction off down here with a starting bid of £ 10 and that was the hammer price of most of them as with thousands of bikes for sale, bidding was not all that keen.
The Indians & Harleys apparently started at £ 15 and a lot did not go much higher.
There was still a shortage of new machines for the home market in the early 50s as the UK concentrated on export to bring in foreign currency...
I would think any company would seek to take advantage of the resultant demand created for ex WD machines that were immediately available...It must have worked as Dawsons ran on for a long time after that, they were still trading around 1970...Ian