Its not until you do a little research that you find that this, in fact, an experimental steam locomotive. It even has a Wikipedia entry…
The Leader was a class of experimental 0-6-6-0T articulated steam locomotive, produced in the United Kingdom to the design of the innovative engineer Oliver Bulleid. The Leader was an attempt to extend the life of steam traction by eliminating many of the operational drawbacks associated with existing steam locomotives. It was intended as a replacement for the ageing fleet of M7 class tank engines still in operation on the Southern Railway (SR). Design work began in 1946 and development continued after the nationalisation of the railways in 1948, under the auspices of British Railways (BR)
A quick search of Google also reveals a couple of scratch built models and a possible Dapol locomotive. What is fascinating is that such a loco was built and that 5 were initially planned as a prrof of concept. Sadly the whole thing failed and all production models were scrapped. What is most striking for me is the driver sitting up at the front and somewhere in the middle is the fireman, this must have felt like the beginning of the end for them.
Other articles: Southern E-Group