Hi, welcome ti GoY, the Jacobite rose is Rosa x Alba, cultivar Alba maxima, semi plena is 1 of the oldest roses known, and R Alba was originally a "sport" of this, Alba Maxima is the double flowered form of the white rose of york, so whatever you call it, it is still a Jacobite rose, Derek.

thanks,(realised I'd put Jabobite),someone said it was a 5 petal rose,so I wasn't sure. I know Prince Charlie was supposed to have picked picked one on route from Glenfinnan to Fort William,and put in his hat.Thanks again-scotsmist