Hi I'm Jake for anyone who missed my "Hello I'm new!" post in the greetings section!
I've noticed a fairly common issue with the 100w versions of the Thorn Beta 79; the entire lampholder support tends to break away from the canopy leaving it laying in the bowl. I've seen a couple with holes in the bowl where the lamp has melted its way through completely! Perhaps the assembly is just too heavy for such a lantern?
Also, almost all of Sheffield's Z9554M lanterns have had their bowls have faded quite badly to the point where the refractors aren't really effective at all. It's strange considering this lantern often replaced failed MA50s which (in my opinion) had a much better refractors and light distribution. (Not to mention that it's not uncommon to see them with a small pond inside the bowl, perhaps this is just the council not securing the bowl properly?)Firstly, welcome to the forum!
Yes at home in Wiltshire, we too have quite a few gear in bowl MA50s that have pools of water sitting in them - We have loads of Z9554Ms and nearly all of them had bowls full of water. A few were so bad that the lamps stopped working. However the council made a decision to source new bowls and fit them onto failing examples and it has made all the difference.
At uni in Ceredigion, there are a few GEC Z9554s though the ones with deep bowls have all been replaced now. The remaining examples are in poor condition with cracked bowls or missing bowls and one is even missing the bowl and the lamp!