Hi Callum,
Thanks for your reply, welcome comments and advice.
I have downloaded and used the beta version as you suggest. The test RW2 image unfortunately still loads with vignetted corners.
I have in this instance saved both RAW and JPEG versions in camera. I have found that the JPEG version direct from the camera is cropped by approximately 13% compared the RW2 image and shows no vignetting.
Using the Lens Correction adjustments within the RAW Develop Persona I adjusted the Scale of the RAW image to 113% and this produces a very similar image the in camera JPEG image and removes the vignetting.
I hope this description is clear and useful.
Regards
Jamie