So a journey such as Birkenhead-London or Liverpool-Croydon wouldn't be included in the Liverpool-London figures? If so, then Manchester's Metrolink might be skewing the figures relative to Merseyrail, since a Metrolink+Avanti journey would have a split ticket at Piccadilly whereas a Merseyrail+Avanti would likely be on a single ticket. Similarly for other places like Glasgow with good suburban rail networks.
There are 18 stations in the London Station Group across 9 boroughs so when its London BR its pretty much all of central London, but Croydon isnt one of them. Page 279 has the figures and its Liverpool BR and Manchester BR, elsewhere when modelling potential demand for destinations from southern WCML stations they model Manchester including Metrolink network coverage as one destination and Liverpool including Stoke and North Staffordshire as another.
They have also modelled abstraction from HS2 completion using the pre-covid figures as if it was completed today.
London BR - Manchester BR £203.9m to £61.6m
London BR - Liverpool BR £84.3m to £59.4m
London BR - Birmingham BR £96.3m to £32.2m
London BR - Chester £27.6m to £17.4m
London BR - Glasgow BR £48.3m to £31.1m
The tables of revenues flows is missing all North WCML stations between Crewe and Glasgow/Edinburgh with the exception of Preston and Liverpool, so for example Warrington, Wigan, Lake District stations, Carlisle etc... are completely absent.