Paul, It did used to be wired with some kind of economy timer, and the fuses in the bottom box are the same rewireable type as in the top box.
I believe this service is acctually 80A, the markings on the RCD say this.
And around here a lot of houses share a spur from the mains, I share one with the house next door, but I've even seen one sharing four or five houses...
