If Tfl are refusing to provide a 1 stage crossing outside this busy station, then they need to provide a larger island projecting into the junction and partly wrapping around the corner.
This would create a safer large holding 'pen' for crossers who would be more visible to traffic and have better lines of sight as well.

The traffic exiting Dartmouth Rd might all have to be directed left into London Rd to accommodate this, but left-only junctions onto main roads are not so uncommon.

Not sure what we do with the 122 or the emergency services. But Tfl have smart people - I'm sure they'd be able to work the small details out.

Alternatively they could spend 10 minutes re-phasing the lights.
Or of course do nothing at all.