Buying cars in the form of a kit was very popular in the early 60ies. Not only TVR, but also Lotus and many other manufacturers shipped their cars a kits and were avoiding some taxes this way. This made a huge difference for the buyers, but also offered them the challenge to finish the manufacturer's job.
Well, this meant a lot of things. First, of course, you had to check whether the kit delivered to your home was complete. On the first picture you see the parts list and the attempt of the buyer to tick off the parts actually delivered.
But even if everything was delivered this didn't mean completing the car was a simple task. Obviously this owner of a TVR Grantura had to "reinvent" the wiring diagram (by hand, see second picture) to make sure everything was correctly connected. In other cases a serious amount of adjustments or welding may have been needed. Especially as many cars were delivered without the gearbox and engine.
The good thing though was that the owner really know what he was driving and probably was able to fix things better than people buying finished cars. A bad aspect may have been on the other side that unskilled owners made a lot of shortcuts or mistakes that had caused bad consequences later during the life of the car.