Greetings one and all, many thanks for all of the helpful comments. Do you remember in your days of youthful thinking whereby every hint that something was amiss had us reaching for the workshop manual ready for a complete strip-down? The solution was normally offered by some wise old sage telling us to look for the simple causes first. It can still apply to us young 75 year-olds! I returned to the dealers, trade plates were fitted, and I went out for a thoroughly superb 20-odd mile jaunt, revelling in the sound. Returned to dealer, wheeled bike into showroom and put its onto the stand. The back wheel turned quite freely!!! When I mentioned that to the proprietor, his reply was along the lines of "They all do that sir, when they come in here". He then showed me where the bike was parked originally, and there was a hard to see shallow dip in the floor. Laughter all round, so I bought the bike! My GB 250 now has a bigger brother. Stay safe. Mike.