Unidentified silver swastika ring -1935

[mike rowan]

I bought this ring on a recent trip thinking that it was probably a repro, but a nicely made one. I cleaned it up a bit as it was very tarnished . A friend had a look at it and pointed out that it had a hallmark and manufacturers mark which I had missed as they were very black and small. A bit more cleaning and strong magnification showed a British hallmark, London 1935 and a RR in a shield which I take to be the manufacturer.

Can anyone identify this ring ?

Many thanks

Mike