Yes - needs to move about a foot (reducing pipe, rather than increasing). Also I might want to replace another modern radiator with reconditioned Victorian one. Do you know of anyone who could do this?
I'm no expert, but I think you'll find that a wide bore Victorian radiator (4 inch pipe) won't be compatible with a modern high pressure half inch radiator system.
Moving the radiator is easy:
To move the radiator, go and buy a pipe freezing kit, freeze the pipes beyond where you want to shorten them to. Drain the radiator, and remove it from the wall.
Move the fittings, cut down the pipe to chosen length, refit radiator to wall, and reattach to system. Remember the frozen pipes won't stay frozen for ever, but that will be an incentive to get the job done before East Enders.
Check for leaks, repressurise system (to make up for the water you've lost from the radiator), bleed the radiator, paint wall, and hey presto, job done.