The old 238 (when it went to Barnwell) did get quite busy around the Seaham to Houghton section. I distinctly remember that a trip (on a Saturday) was split into 3 sections:
Sunderland to Ryhope Village (1 trip number)
Ryhope Village to Houghton (another number - I believe this was supported financially)
Houghton to Barnwell (another trip number and also supported)
Northlea in Seaham was always busy but you can't get anything bigger than a Solo around there.
Regarding the 61, I believe this to be branded Mercs from what I've seen
RE: September Service Changes