To add fuel to the fire re: cat deterrent devices that do /donot work...
The 'cut-out cat' silhouette designs shown in various gardening mags struck me as 'probaby a good idea', but hellishly expensive AND I'd rather make my own from a lino offcut, matt black emulsion paint (two thick coats on both sides) and two jewel-like cats-eyes used in the bottom of plant pot outers for drainage... (or use clear glas marbles and two or three dabs of superglue.
"Mogg1" and "Mogg2" etc are still 'on guard' in the garden two years down the line.
I made three and placed them strategically around my garden, propped up with three lengths of bamboo - two to one side & one on 'tother. *I keep a 'spare' one in our downstairsbathroom window, just to give the impression that there's a ferocious 'mog' resident in the house too!
Cat 'incursion' + 'presents' still occurs,every now and then. I aso use holly, berberis, cotoneaster clippings ....on troughs, tubs & freshly-turned/ planted soil areas......do you get my 'point'??