The extension of the Bakerloo line is the most cost effecient transport improvement that could be made in all of Britain. Bakerloo line is the only line that is not at full capacity when it reaches zone 1 since it only starts at E&C.

The tunnel already goes half way to Camberwell where there is a overground site ready for the station, currently a car repair shop. The trains can then go overground on existing rails to Crofton Park or a new interchange station at Brockley (Brockley High Level), Catford/Lewisham, then on to Hayes via a connection with TramLink.

The capacity of this route is better than could be provided by any other similar scheme of similar cost, as there is little infrastructure changes required, just a little tunnelling and a couple of new stations. It would be substantially less that the cost of ELLX. And it would relieve a number of overcrowded train lines.

This isn't a new idea. It was first around in 1931 and it even has its own page on wikipedia http://en.wikipedia.org/wiki/Bakerloo_li...Camberwell

Of course my preferred route is to go underground all the way and follow the Walworth Road through Camberwell, Denmark Hill, East Dulwich, Forest Hill, Bell Green, Beckenham, Bromley. If we were in North London we would expect no less.