Machine 624 was despatched on 12-7-55, the agent was Farmfitters, unfortunately the customer details are not recorded for this machine. Series 3 production ran from 1954 to 1965.
I have manuals and engine information, Geo Monro is my speciality. I also have the factory records and can date machines from the machine number. pm sent with more info.
Green Spark Plug Company will list alternative spark plugs. They also sell HT cable and terminals.
The Museum of English Rural Life (MERL) at Reading hold the factory records which will give you date of machine.
Looking very smart. I see it has the optional large silencer rather than the standard pepper pot type. For control cables I buy inner and outer along with nipples, ferrules etc from motorcycle parts suppliers. I have used both Feked.com and Trialsbits.