Thanks everyone for the comments. It is a Model 99, per stamp on the barrells. Using some of the keywords from the posts above a Google search now leads me to believe that it is from 1964 or possibly '65. Have not fired it from a bench yet, will do so when the weather is more pleasant. However, it seems accurate by the results of the 50 or so rounds I put through it in my garden. No jamming/misfires.
Although I know it is not valuable, I think it might have some potential in the beauty stakes. Dress it up a bit, like in those films when the frumpy schoolmistress lets down her hair and removes her reading glasses..... you get the idea!
Rs
K.
