As everyone seem to have ideas about extending the Waterloo & City Line, I’ll throw my hat into the ring.

You make the line to Bank a spur, add a station near to Cannon Street (City?) or a bit further along, the continue the line to Fenchurch Street.

Fenchurch St gets a tube connection, double the platforms in the City, more demand outside of the peaks. You can even have 3 shuttles between Waterloo- Bank/City and Fenchurch St-City

Either that or have turn backs past the platforms and Waterloo to allow 2 trains in platforms whilst the 3rd is turned around

I know it will probably never happen as TfL have bigger fish to fry, but the crayon chewer in me likes it