Blackwall Tunnel average speed limit sign says 20mph

I noticed a new sign at the Blackwall Tunnel this morning stating there was an average speed limit of 20 mph through the tunnel. I have seen other posts about cameras in the tunnel - anyone know if these are forward facing?

When I went through it on Sat the cameras had black bags round them so I dont think their active yet unless they’ve been taken off since Sat

ouch… it is hard to maintain 30mph in there… loads and loads of people will get stung. thanks for the headsup.