Join Date: Mar 2010
Location: Ontario, Canada
The most effective way to stop him from spraying would be to have him neutered. Given that he's 3 years old, even neutering might not help, although I have heard that about 80% of older male cats will stop spraying within about 6 months of being neutered. So, it's likely your best bet. In the meantime, you might also try Feliway (a pheromone product).
To remove the odor, you should use an enzyme-based cleaner intended to remove smell/stains from cat urine, such as Nature's Miracle. I'm not sure if that's available in the UK...if not, you can ask your local pet store for an enzyme-based cleaner for cat spray/urine.