Bletchley Traction Depot

In this months Railway Magazine there is a picture of the front of
Bletchley depot with the accompanying caption
“Bletchley traction depot closed on May 31 when operations transferred
to Northampton, but its last day was marked by an unusual ‘first’ when
ex-LMS Pacific No. 6233 visited the depot. The shed is to be used for
the storage of London Tube stock.

Does anyone know what London tube stock is going to be stored there?

John Burke
WRUG