A while ago I posted a message about traction used on the last day of the Rugby-Peterborough East service, based on RO reports and pictures on flickr. That message is here: view topic php? f=2&t=380
Recently I looked at the RCTS mystery photograph collection, which has many pictures of the Rugby-Peterborough East route. There's nothing for the last day, 4 June 1966, but some coverage for all 4 Saturdays in May 1966 plus some other dates. The gen for the 4 Saturdays in May 1966 is:
0636 Rugby-Peterborough East not known all 4 dates presumably too early!
0855 Birmingham-Ely BRCW 3car+MetCam 3car; Park Royal 2 car+ unid 3 car; BRCW 3car+MetCam 3car; not known.
1233 SO Rugby-Peterborough East: Brush T2; Brush T2 (skinhead); Brush T2; EE T4.
1347 Rugby-Peterborough East: not known; not known; BR T2; EE T4.
1555 Birmingham-Yarmouth BR T2; BR T2; not known; not known.
1729 Rugby-Peterborough East: BR T2; BR T2; BR T2; EE T4.
2053 Rugby-Peterborough East: not known all 4 dates presumably too late!
0705 Peterborough East-Rugby: not known all 4 dates presumably too early!
0725 Yarmouth-Birmingham: BR T2; not known; BR T2; not known.
1224 Ely-Birmingham: MetCam 3car+BRCW 3car; unid 3 car+Park Royal 2 car; MetCam 3car+BRCW 3car; BRCW 3car+unid 3car.
1240 Harwich-Rugby: BR T2; EE T4; BR T2; EE T4.
1818 Peterborough East-Rugby: not known; not known; Brush T2; BR T2.
2012 Peterborough East-Rugby: not known all 4 dates presumably too late!
There's a few areas where the information may be available to fill gaps:
Many but not all pictures have comments posted by Frank Berridge that identify the trains and dates, suggesting access to the photographer's notes which may also record the missing trains;
I have been unable to put a date to the pictures in films 65-035 and 66-33;
There's missing frame numbers in most films, presumably images too poor for reproduction, but it might still be possible to identify train and type of traction.
Finally, I have a theory about the formation of the Harwich Town-Rugby train, which attracted a number of comments on the mystery photographs. I suggest that the stock working 1233 SO Rugby-Peterborough East is banged onto the back of the Harwich Town-Rugby at Peterborough East to get it back to Rugby.

I now have a bit more information, particularly on the eastbound trains from Rugby,
and this is a revised version.i hope its helps you.
0636 Rugby-March not known
0855 Birmingham-Ely 6 car BRCW dmu
1233 Rugby-Peterborough D5145
1347 Rugby-Peterborough D5522
1555 Birmingham-Yarmouth D5085 to Peterborough D5526 forward
1729 Rugby-Peterborough D5010 (returned light engine)
2053 Rugby-Peterborough D5036
0705 Peterborough-Rugby not known
0725 Yarmouth-Birmingham not known
1224 Ely-Birmingham 6 car BRCW dmu
1240 Harwich-Rugby D5145 forward from Peterborough
1818 Peterborough-Rugby D5036
2012 Peterborough-Rugby D5085