A celeb standing in an election wouldn't normally be that interesting, but there's a couple of things to consider about this if it happens:-
1) Liverpool's one of those areas of the country with a very strong self-identity. Posting someone who's never heard of Bill Shankly or Gerry and the Pacemakers strikes me as a bad decision.
2) Ricky Tomlinson's a local boy made good and can probably make a decent speech.
3) It's not a particularly strong Labour seat. Labour had 5000 more votes at the last election than the Lib Dems. That's already going to get taken down a little by the fact that Labour are struggling and dropping in a new candidate.
So, could Ricky Tomlinson fight the seat, split the Labour vote and let the Lib Dems in? Could be interesting...