Nothing retro, unless your neighbour votes as well, or Returning Officer knows/recognises you or your neighbour - in which case you would be prosecuted and punished.
retro - nothing really. When i got my first grown up job and moved to another area, it was in a general election year, just around april or may time. I was still on the electoral roll at home, but there were voting cards in my new place for the person who had lived there before, so i just used that and voted in my new area!
Even if the presiding officer recognises you he cannot prevent you from voting if you insist you are your neighbour (unless your neighbour has already voted)
It will be made quite clear in the process that you are committing an offence though