The machine in the first of Hopkirk's pictures is an early Mark 1 TV175 "widestyle". The widestyles were produced until about 1963 after which the "slimstyles" took over. You can tell it is a Mark 1 because the headlamp is fixed on the front bodywork. Later models had the headlamp in the centre of the handlebars meaning it swivelled as the bike was steered. You can tell it is a TV (rather than an Li125 or Li150 which looked almost identical) because the front suspension has a damper, which the Li's did not. There was also the LD 125 produced at that time and this could be distinguished by the bodywork. On the TV and Li the top of the bodywork on which the saddle sat was near horizontal (in earlier models 2 individual saddles were provided by latterly a single long one was provided - much more cosy with a girl on the back). On the LD the bodywork sloped sharply down behind the front seat to a pillion seat situated at a lower level. (Very early LDs and the even earlier D had no side panels and all the works were visible. It became a trend in my scooter days for some owners of older bikes to make them into "stripdowns" by removing the bodywork).The LD was a much earlier design and also had a different engine layout. Its cylinder was vertical whereas all later models (the Li, TV, GT200 and SX200) had their cylinders lying horizontally leaving room beneath the saddle for a small luggage box (which was big enough to accommodate a plug spanner and a cheese sandwich).
The introduction of the slimstyles saw major changes in appearance but not much mechanically. (In fact the engines from slimstyles could readily be fitted in the widestyles) However, the TV was upgraded to 200cc and in the UK was marketed as the GT200. This was developed into the Special X 200 (SX200),
I owned a 1961 Widestyle Li150 and then bought a brand new SX200 in 1968. If I remember it cost me about £225 (when I was taking home about £40 a month). A firm called Arthur Francis in Watford provided upgrades to these machines and I had mine bored out to 225cc, and had a "Wal Phillips" fuel injector (in fact it was just a choke tube) and 12v electrics fitted. I did have a spare wheel (on a rack at the rear) and four "Oscar" spotlamps (my 12v lighting opened up a range of lights not available to 6v machines). It was an attractive beast and covered about 10,000 miles on it before some thieving b'stard nicked it. I was able to buy a second hand Mini with the insurance payout and my scooter days came to an end. Today in good nick my bike would go for about £10k
Happy Days! But I really ought to get out more.