Cats are protected under the Animal Welfare Act 2006 in England and Wales and the Animal Health and Welfare Act of 2006 which applies in Scotland. The penalties for comnitting an act of cruelty, can include a fine of up to £20,000 or a six-month prison sentence.
The cat welfare charity Cats Protection offers advice on how to humanely keep unwanted cats out of your garden and property.
To discourage cats from entering your garden:
Shoo him away by either shouting or clapping your hands
Squirt water at him using a low-powered water pistol (not a super soaker), being careful to avoid his eyes
Install an automatic garden spray that is triggered by an infra-red detector that locates movement
Erect high, close-boarded fences next to the hedges in the garden, making it difficult for cats to visit.
Try not to leave food for birds and other wildlife in places that are easily accessible to cats and also ensure dustbin lids are secure. In addition, do not start feeding a cat if you do not want him around.
To stop cats toileting in your garden:
Cultivate shrubs closely to prevent cats from finding a place to dig.
Spread chicken manure around beds and borders, taking care to use Soil Association approved pellets rather than fresh manure.
Consider covering parts of the garden that you do not want the cat to toilet in with stone chippings, pebbles or small rocks.
Olbas Oil soaked teabags, lion dung-infused pellets, the planting of coleus canina and crushed egg shells have been used with varying levels of success to deter cats from toileting in flower beds.
Hardy plants and the use of tall planters in strategically placed positions (entrances, protruding corners) can help to reduce the effects of cats marking their territory through spraying.
Whether people like cats or not, humane deterrents should always be used.
See also
Get rid of unwanted cats in your garden
Get rid of unwanted cats
Getting rid of stray cats