"Andy" wrote in message


The 'class' date of underground stock used to be the year of the
order, not the year of entry into service, the 2009 stock breaks this
'rule' but I think it applies to most of the other tube stock classes.

No it wasn't the date of the order, which was usually years earlier. I
think it was the earliest anticipated date of entry into service, but
the actual dates often slipped by a year or two.

So, for example, the 1959, A60 and 1972 stocks really did enter service
in their nominal years, but the 1973 stock didn't enter service until
1975 and the 1992 stock in 1993. By introducing the single late night
train into passenger service, posterity will record that the 2009 stock
entered service on time.