Highly unlikely Ian, but the way things are changing it's a possibility. I've never heard/seen a Willow warbler before early April.
No streaks on a Chiffchaff.
Have you thought of Twite? https://www.rspb.org.uk/birds-and-wi...ite/index.aspx
Or, more likely at Heysham, Rock pipit https://www.rspb.org.uk/birds-and-wi...z/r/rockpipit/