It's a switched fused connection unit, but I can't find one with 2 switches. Best bet would be a proper electronics shop. They might not have one but they'd probably know where to get one.
What does that switch control? Is it lights, your immersion heater, a washing machine? Given that it's a double then I assume that it's a light switch that runs off the mains rather than the lighting circuit? I think they are called FCUs (Fused Connection Units), or in this case switched FCUs. Units with two switches are fairly unusual, though, it would seem. Disclaimer: not an electrician
The clearly exist, but like hell can i find one... like @The_Crapman said, they all seem to come with just the one switch [or no switch].
They once existed but they may no longer. Building codes change and the double switch may no longer be available for sale. I'd check with a proper electrical supply shop. How old is the switch in the photo?
Thanks for all the replies and apologies for the delay in replying - had a busy, but lovely, family weekend. I think that will have to be the next port of call as I'm still drawing a blank. We have two in the house actually. Both are outside bathrooms with the right-hand switch controlling the main light in the bathroom and the left-hand switch controlling the extractor fan. The left hand switch of this particular one is connected to a combination shower light and extractor fan. Presumably the fact that it's connected to an extractor is the reason for the fuse. Still no joy there unfortunately (well at least my searches there are not coming up with anything) The house was built in 2004 so they're a maximum of 15 years old. Maybe you're right - maybe they're not available any more...
Grid switch Part no as follows Mk k3703 x1 Mk k3633whi x1 Mk k4882whi x2 Mk k4890whi x1 That will make up that part mate
Not quite sure how I missed this - that would be awesome No wonder I couldn't find a replacement when it's actually a grid switch with parts added. I'll drop you a PM now and we can get something sorted out.