Tough to say. His margin of victory in 2017 was comparable to nearby Hyndburn and Burnley which both went Tory, however his didn't vote quite as heavily leave as those two and West Lancashire which voted leave in similar numbers stayed Labour, so I think it could have gone either way. The swing towards Tories overall was strong enough his would have been vulnerable, but there were also more marginal ones nearby like Wirral West, Weaver Vale which Labour managed to hold onto while Lancaster and Fleetwood had similar margins and also stayed Labour. So I would say it is a 50/50.
It would it depend on two things how well are the Lib Dem’s doing and of the brexit party contest the seat.