I remember my great aunt had one of these from the co-operative insurance well into the 1970's the insurance man would collect the money every quarter and log the amount in a payment book I also remember my grandma had a television that ran off 10 pence pieces to cover the cost of rental it would always go off half way through a program and every one would scramble around there pockets for 10p, the joys of life before direct debit.
I see them in auctions maybe one or two a year they fetch between 15-20,000 so should imagine they retail at £30,000 plus, very nice if I win the lottery, the only top quality English platform escapement I have is by Brockbank and Atkins which is huge in comparison to a french platform.
The one in the link above clock numbered 12616 is exactly the same as the one I have but mine is number 12617 I have it on the wall in my bedroom.
I also have a 6mm lathe although mine is a Lorch. I bought it second hand and seem to have been lucky as it works surprisingly well for what I use it for.
However, the previous owner managed to make a repair to a very similar problem by putting a right angled piece of metal in and tapped holes in the casting to hold it together. It works well although it is very tight fitting now so it is a bit of a pain to take on and off. Fortunately I don't use the cross slide very much and prefer the hand held graver.
I haven't cleaned everything yet but here is a picture of the repair:
Failing that, cast materials will braze as long as you are careful with the temperature which is another possible way of repairing it. I haven't done much brazing, welding or silver soldering before so I don't know about the practicality of that idea.