Just spotted this on a local forum, though it might be helpful here :)
Free Bullie Breed Neutering
No questions asked.
For the month of July 2011 we are offering free neutering for any Bull Breed.
Please contact one of the following vets to book your dog in for free neutering.
Twickenham Veterinary Surgery, Hampton Rd - 0208-898-0528
Richmond Veterinary Surgery, Kew Rd - 0208-940-0986
Dene Park, Whitton, 0208-898-0008
Medivet, Twickenham, 0208-892-6300
This is being organised through Animal Rescue and Care