I am not trying to denegrate this machine, only to point out that it is not original.
Frame number 61-3919 is definately a 1961 24MCS machine. You can check this on
www.greeves-riders.org.uk.
The motor does not look like a 9E as it has the clip on pressed aluminium flywheel cover when most 9E motors had the flywheel covered with a cast cover attached with screws.
The motor fitted is either a 6E or 8E, and it has a 3 speed gearbox, not 4 speed as fitted to most Greeves. The 6E/8E motors are from the mid 1950's.
Also "nylock" nuts? These were not used by Greeves during original assembly.
This is a good restoration that would fit with most bike collections, but the originality is not there.
Photo of a 24MCS rolling frame. Note the Greeves "paddle" brakes fitted as standard.