The second red wire isn't connected to anything, it's just floating around behind the switch/socket looking lonely.
Maybe some history... Had a bloke in today who was there to fit some light fixtures and swap some single sockets into doubles.
He got the first room upstairs done, no problems, lights and sockets work great.
Heads into the second bedroom, swaps the lights/sockets... no leccy.
He decides to have a look round to see if there is a break in any of the lines.
So he checks the switch ( which was hanging from the wall ) and sees the red neutral and yellow green connected, then spies the lonely red wire hiding behind, so he pops around to the other side of the wall to where a socket is in the exact same state.
He's not sure if it was a looped wire that was cut and never re-connected or if it's an old dead line, or if it's faulty ect.
So he decides its not safe to proceed with the rest of the lights and sockets/swtiches, until he can find out what this red live wire is for, why its there, what its doing.
I did some reading and I suspect it was a looped wire which was cut and never reconnected.
We bought the house in a dire state, most of the sockets and switches are fine, connected ect. but these two were left dangling and we're not sure why...probably because of this extra live wire. We've NOT had all of the electricity on in the house at once. Our consumer unit consists of.... 6 or 7 circuits/fuses one for the lights, one for the plugs, one for the boiler, one for the cooker, a spare, and one other that I am not sure at the moment what is for.....
its all a bit confusing tbh