Unwelcome 'boyfriend'

[frankie]

For the past week a big black cat has come calling outside the catflap for my 16 yr old KatyKat in the evenings.  She had previously been traumatised by my 2 Burmese brothers, who both sadly crossed the Rainbow Bridge 3 weeks apart earlier this year.  KatyKat was just getting her confidence back and going outside without me but she now will not go through the catflap.  She swears at him (he's really not her type) through the catflap, she must smell him as she is now blind, while I galvanise myself to go out and hiss at her unwanted suitor.  By the time I unlock the door he has started to run away, so I cannot catch him or spray him with water. 
Any ideas how I can deter this big lad from jumping the 6ft fence to get to Katy?

Removed extra spaces 

[JessicaH]

Sure are some nasty Toms about these days 
Hope you get it sorted ASAP.

[frankie]

I am sure he isn't nasty, it is just that KatyKat cannot see and was just beginning to venture outside on her own.  We are now back to going out together (she stands by the catflap until I go with her).
He, the black enemy, was just peering in off the spiral staircase into my bedroom, so he's a voyeur as well... 

[Roscoe]

Get a spray bottle of water and squirt hump   

[Judi_bk]

We have water pistols

[frankie]

Usually by the time I get to the door, unlock it and go out, he is about to leap over the 5ft chain link fence, so water is not an option.  Other than hissing very loudly at him I cannot see what I can do apart from hope he finds a lady friend elsewhere and soon....
At any other time and if I did not have a bind cat, I would encourage him, get his packed lunch removed and adopt him.