How to claim our garden back from neighbours cat?

[chocolateygoo]

We have just got a new cat from the local rescue centre, a lovely 9 month old male who is settling in well all things considered (1 yr old and 3 yr old DCs to get used to!) He's never been outside so we're going to take things very slowly although he will need to get used to it at some point as we have the conservatory doors open all day long over the summer.

However - there is already a cat in our garden! He's been there most days since we moved in about 2 years ago, he likes to sunbathe on the shed roof. He's quite aggressive to other neighbours cats who sometimes come through the garden.

I want to get him out of the habit of using our garden so that there aren't any issues when our cat starts to venture out. Any ideas on how to do this? Thanks!

Also - am a complete cat owner novice, any recommendations for good cat books?

[PipkinsPal]

A water pistol and some prickly plant offcuts on your shed roof as a starting point.

[amidaiwish]

Watching.... All our neighbours have cats, drive me mad.