This is Burnet Rose, Rosa pimpinellifolia, growing in dunes at Llangennith at the end of Gower. There were no cream flowers at the end of August when this photo was taken, but the distinctive black globose fruit and red stems with red-tinged leaves are distinctive.
The Roses are one of the trickiest groups to identify accurately. There is a whole BSBI Handbook devoted to the matter by the inestimable Rev Dr Anthony Primavesi. They also hybridise, further complicating the issue.