On Nov 24, 12:00*am, Mizter T wrote:
[snip]
(b) there was wider disruption on the WCML, of which the disruption to
Southern services from the WLL up to MKC was only a part (just how
disruptive was this disruption at Watford Junction?).
[snip]

Answering my own question (inadvertently I must admit - I was looking
on the LM website for something else!) - from the front page of London
Midland's site:

---quote---
This is an important announcement

Thank you for your patience during this morning's disruption

If you were caught up in the disruption around Watford Junction today,
please accept our sincere apologies.

A maintenance train damaged the track at an important junction south
of the station which prevented any trains from accessing the St Albans
Abbey line. In addition, the incident blocked two of the 4 lines
between Watford and Euston, which was further complicated by a
signalling problem at Wembley.

While Network Rail worked to reopen the lines, both Virgin Trains and
ourselves ran a special timetable with fewer trains until
approximately 0830 to reduce congestion. We also ran buses on the St
Albans line until 0930.

Once again, please accept our apologies if your journey was disrupted.
If you were delayed by more than 30 minutes, remember you can claim
compensation under the Delay Repay scheme.

For the latest updates during disruption visit nationalrail.co.uk/
disruption or if you use Twitter, follow us @londonmidland.
---/quote---