Address
Prince Arthur
80-82 Eversholt Street, Euston, London, NW1 1BX
Location
Walk north up Eversholt Street, which is the road on the east hand side of Euston station. Walk past the, err, gentleman's night club and the Post Office depot and the pub is a few hundred meters up on the right (east) of the road. That's it.
By Tube
Euston is on the Northern and Victoria lines and the pub is within walking distance of Kings Cross and Euston Square (District, Circle and Metropolitan). It's not far from Mornington Crescent or Warren Street either.
By Bus
A bewildering number of buses turn up to Euston and it's pointless me enumerating them.
This spider map from Transport for London has a list.
Info
Good ales, a decent selection of whisk(e?)ys and some really nice Thai food.