I don't think you realize how happy I am that your tee is names 'Union Flag TARDIS' because I have this little pet hate of when the Union Flag is never named correctly. It's just a petty little thing, but you've made my day :D
I used to get it wrong, but there’s always Idiot’s Lantern to remind us xD
“Rose: That’s the Union Flag. It’s the Union Jack only when it’s flown at sea.”
Did the furnace break or would it not actually let you? If it worked, but displayed that message, then don’t worry about it. If it didn’t work…let me know because that’s really weird. Either way I’ll look into it when I get home tonight.