In message , Philip
Hardy writes

How long was T4 out of service, until late 2006?

BAA never took the T4 out of service while the underground station was
upgraded ;-)

In reality, very little work was done to the T4 station other than a bit
of a deep clean.

The work was to create the junction for the T5 line and trains couldn't
run
through T4 whilst this was happening, it was not to upgrade T4.
--
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