Decent toilet wank around Great Portland Street / Marylebone / Kings Cross

I'm struggling here guys - I want a decent wank at a toilet near by - but I'm having no luck.

I tried down at Great Marborough Street next to Liberties - lots of chaps trying but with the screens and cameras it's almost impossible to do things properly.

I've had great luck with the toilets at Old Street Tube - but that's to far away.

I head home / out at lunch time from Great Portland Street - I've tried the toilets there but nothing happening - and then onto Marylebone train station - again nothing happening - does anyone know of anything in between? Somewhere fun around Tottenham Court Road perhaps?

Desperate for a good wank