Hunch. In the wider record, Rugby's Christmas works in 2007 ran four days late, so a longer delay has happened before.
The 5 January Paddington market resolves YES on the same terms if full GWR service into Paddington runs from the start of service on Tuesday 5 January 2027. Service still limited by the works on that day is NO, and the Guardian and BBC News are the backup.
We looked for cases where Network Rail closed a main London station or Birmingham New Street for holiday works that put in new equipment, and named a reopening day that was the first working day after the holiday. We found five such closures since 2007, all in London. Three reopened in full on the morning Network Rail had named.