Hi Flint,
I think it a is a FLZ original V break action with side lever breech lock,
I see the serial No is 375,if you look in Danny Garvin's gallery you can see mine which is serial 481.
I think these are quite rare,very well made with deep blue finish and very good power.
481 has a brass FLZ medallion inlet into the left side of the stock which is not on the example shown in your post.
All in all a very nice rifle,
ATB,
Chris