THink you might be right (though by now possibly a bit longer ago than that). They weren't under ground so wouldn't have come under the post-Kings Cross replacement requirements.Didn't Greenford have the last wooden ones until about 10 years ago?
I seem to recall that after the Kings Cross fire, the remaining wooden ones got metal side panelling, as the fire risk (the "trench effect") was more to do with this area than with the steps themselves.Marylebone had wooden escalators in 2002 when I used the station semi regularly. I'm not sure of the exact date when they were replaced.
The old wooden escalators certainly had character and style but given modern safety standards they had to go.
At the London Transport Museum depot they have part of an old wooden escalator preserved if anyone is intrested in seeing at least part of how they were.
I think the sides were metal but cannot remember for certain.I seem to recall that after the Kings Cross fire, the remaining wooden ones got metal side panelling, as the fire risk (the "trench effect") was more to do with this area than with the steps themselves.