Yup, inter terminal shuttles are planned (all using HX stock) but nothing out onto the GWML towards Paddington at all. (which is fairly standard for Boxing Day outside of global pandemics, they didn't run anything at all on Boxing Day 2020/2021 I don't think)By the looks of it, there will be a service between terminals but nothing to Paddington. May be wrong though.
That’s my kind of ChristmasI stayed at a large Heathrow hotel at Christmas a few years ago to escape a family Christmas & took the Heathrow Express into Paddington on Boxing Day for something to do.
That’s my kind of Christmas![]()