I don’t think you will get very far with an argument about inadequate signage. As well as that, you really need to concentrate on a single aspect of your defence rather than have a “shopping basket” of deficiencies that you will be asking the court to consider.
I think you need to investigate the history behind the two Traffic Orders.
The one cited by PC Wilson in his evidence pack (The Kingston upon Thames (20 mph Speed Limit) (No. 5) Traffic Order 2023) seems to include Kingston Hill in its entirety.
However, the one I found (The Kingston upon Thames (20mph Speed Limit) No. 1) Traffic Order 2024) mentions a specific section of that road, namely “Kingston Hill between its junction with Queens Road and a point 150 metres east of its junction with Warren Road”.
It seems from “tittle tattle” that Kingston Hill was omitted from the earlier Order. According to the tittle tattle, there was debate surrounding where a 20mph limit should commence (in the direction towards Kingston town centre) and so Kingston Hill was left out of the otherwise almost blanket 20mph imposition whilst a study could be undertaken. My suspicion that Kingston Hill was left out of the earlier order may well be true because otherwise there would be no point in making the later, more specific order.
I think you should contact Kingston Council (020 8547 5000 between 9am and 5pm Mondays to Fridays, according to their website) to gain sight of both these orders.
If the earlier order excludes Kingston Hill then the evidence provided by PC Wilson does not support the charge but I would imagine that error could be rectified in court.
If so, that leaves the question of where the limit actually begins and how that ties in with the placement of the terminal signs. The difficulty with that, as I mentioned earlier, is that the point that is 150 metres east of Kingston Hill’s junction with Warren Road is not on Kingston Hill at all, but probably somewhere in the gardens towards the end of nearby Eastcotte Close.