http://www.bbc.co.uk/news/uk-england-london-11806092

I bet Comrade Crow cannot wait for the date of the Royal Wedding. I am
sure he will be able to concoct a good excuse to go on strike then.
Perhaps it was him who, in a previous life, organised the bus strike
of 1937 which coincided with the coronation of King George VI,

Seriously though, in the two cases mentioned above, there are ongoing
disciplinary proceedings, and presumably the RMT signed up to these
procedures. It seems to me that they are using the threat of a strike
as a negotiating tool.