In reply to M0DDC:
Why one would climb 2000+ ft and then steal a bit of brass defeats me!
Why? To add to the collection of top caps. That’s why!
There’s several different designs been used over the years and a complete collection of all types is valuable. Even more valuable is a Flush Bracket. Luckily for those of us who appreciate the historical importance of a trig point, the concrete used by the OS was damn fine stuff mostly and removing the bracket requires a vandal bring a considerable number of “implements of destruction” along with him.
You can see that over time, the quality of concrete used declined. Some 1936/37 vintage trigs in exposed places are in perfect condition still. Even ones frequently visited. Later trigs show cost accounting had been appiled as the concrete has not stood up to the weather. Vanessa columns have suffered more, partly because they are in the more exposed positions and partly because of their affinity for attracting lightening strikes.
For the record, I have no top caps, flush brackets. Just photos and a fascination with the engineering and maths behind mapping a country.