I always sent mine here, but just check whether Evans in the Cattle Market do it?

Lister Shearing Equipment Ltd

Long Street
Dursley
Gloucestershire
GL11 4HR
UK

Tel: +44 (0)1453 544 832
Fax: +44 (0)1453 545 110
Email: info@lister-shearing.com

Yep i'm pretty sure Evans' & also RM Jones in the cattle market both do blade sharpening.