London Underground building a glazed cube at Euston

A rather tired old office block is to be replaced with a large glazed cube which will be disguising a new ventilation shaft for the Northern line tunnels at Euston.It’s being provided by High Speed 2 railway, as they are demolishing an old ticket hall from the early days of the London Underground which was repurposed into a ventilation shaft of its own and also housed an electricity substation.
With that building going, a replacement was needed, and they’ve identified a side street a