FYI, Justin, all Rover Vortex 7-spoke wheels are 18". The similar looking but 5-spoke ones, fitted as standard to the R75V8, were 17" Star Spoke.
All Factory fitted V8 wheels in both sizes, should have been diamond cut and clear lacquered, but I think none of the 100th anniversary Premium grilled, non-V8, cars were (Germany, Belgium, Switzerland and mostly diesels). They were fitted ex-factory with Star Spokes, but painted not diamond cut. I think all wheels sold as 'spare parts' by MGR, X-Part etc were painted too, but not 100% sure on that.
David