This is parking underneath Euston mainline station. here's some info extracted form their website.
Parking
There is a secured car park underneath the station which is accessible via the stairs by the Underground. Vehicle access is from Melton Street. Disabled spaces are available and additional assistance can be requested to and from the car park. Post code is NW1 2RT.
APCOA manages parking facilities at Euston. They can be contacted on 08450774224.
The fee for up to 1 hour is £6.
Tariffs
Up to 1 hour
£6.00
Up to 2 hours
£8.00
Up to 3 hours
£10.00
Up to 6 hours
£14.00
Up to 9 hours
£16.00
Up to 12 hours
£20.00
Up to 24 hours
£22.00
Motorcycles
£4.00
Whole Day Rate Saturday or Sunday
http://www.networkrail.co.uk/aspx/819.aspx
