Wanderingjew698 wrote:
The snag is that Great Portland Street has no train service most
weekends at present.


Why is that?

Because of ongoing work to enlarge Kings Cross St Pancras station in
connection with the Channel Tunnel Rail Link, there are no trains on the
Circle and associated lines between Baker Street and Liverpool Street.
During the week before your journey, you need to check the situation at
http://tube.tfl.gov.uk/content/nexus/ (Scroll down to Longterm Information
/ Weekend Travel Changes)

The nearest alternative stations are Regents Park and Warren Street.
Alternative routes are Piccadilly to Piccadilly Circus, then Bakerloo to
Regents Park; or Piccadilly to Leicester Square, Northern to Warren Street.
However, both the interchanges involve steps.

Least hassle (but more expensive) would be Heathrow Express to Paddington
(£13 single), then a taxi to Great Portland Street which is not more than 2
miles.
--
Richard J.
(to e-mail me, swap uk and yon in address)