Door tread plate of a London Underground train showing that it was manufactured by <a href="https://en.wikipedia.org/wiki/Metro_Cammell" class="extiw" title="en:Metro Cammell">Metro Cammell</a> during 1973 (n.b. this is not necessarily <a href="https://en.wikipedia.org/wiki/London_Underground_1973_Stock" class="extiw" title="en:London Underground 1973 Stock">1973 Stock</a>, since some of the <a href="https://en.wikipedia.org/wiki/London_Underground_1972_Stock" class="extiw" title="en:London Underground 1972 Stock">1972 Stock</a> was built in 1973)
<a href="//commons.wikimedia.org/wiki/User:Eduap" title="User:Eduap">User:Eduap</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>