Thanks Dave, the storage heaters were the cause! We'd plugged a kettle in and it was working no problem so was definitely just getting a proper supply. Thanks for getting me sorted, much appreciated. One more strange house thing ticked off...
Since moving into our house we've noticed some strange things with the electrics but today I decided I would be useful and try and figure out which breaker on the consumer unit controlled which sockets / lights in the house. My first step was to turn everything off, literally every single switch...
