After the derisory offer of 4% the RMT are going out again, from the 24th to the 27th of December.
14 train companies plus the Network Rail across the country (who maintain and operate signals and track).
Strike is from 6pm on 24th of December so the already early finishing Christmas Eve services will be ending way earlier. I wouldn't rely on anything after noon, and probably earlier.
No trains anyway on Christmas Day.
No trains on Boxing Day.
Few if any on the 27th.
Sorry. It was looking so promising until they made that offer.
The already scheduled 48 hour strikes previously announced, and mentioned here, are still going ahead too.
UPDATE Dec 20th. The strikes are going ahead, and for the 48 hour strikes in January the ASLEF Drivers union are also going out on the 5th. So in Jan, so far, 3rd and 4th RMT, 5th ASLEF against 15 companies, 6th and 7th RMT again. A full week of severe disruption.