As Jack has already eluded to and as such I concur with him that your machine was probably built November~December 1971 which was at the height of domestic cylinder cut machines being made by the Scott Bonnar company. Thanks for adding that air cowl photo as it holds the secrets regarding the build dates of these machines.
Cheers, BB.
I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.
