The mystery of the uprooted grevillea

I've just been replanting my front garden (I find front gardens so much more challenging than back gardens, but that's a subject for another post). The main reason for this was that I had a lot of rosemary that had suffered from a mass attack of rosemary beetle. I don't like using pesticides, especially on something people might eat, so I decided to take the rosemary out. It was getting a bit old and leggy anyway.
I liked the contrast of the rosemary foliage with the phormiums in the front garden, however, so I decided to include a grevillea in the new planting scheme. I chose Grevillea alpina 'Olympic Flame' as I didn't want anything too big. It grows to about 5-6ft, unlike 'Canberra Gem', another cultivar commonly available here, which can get up to 8-10ft.
I like grevilleas. The ones that are hardy in the UK seem to be as tough as old boots, although their spidery red flowers and bright green needles make them look rather exotic. I planted my new acquisition, stood back to admire the effect, and didn't give it another thought until yesterday, when I noticed that it had been uprooted.
My first thought was that a fox (there are dozens round here) or a dog had been digging there. But there wasn't too much mess around, which you usually get when an animal has been excavating. The plant was sitting rather neatly on top of the soil. My second thought was that someone had tried to nick it, but been disturbed before they could make off with their ill-gotten grevillea. But that seemed strange too; why that particular plant, when there are lots of plants in the front garden in pots, which are far more easily nickable?
My final theory was that someone had tried to break off a bit, thinking it was rosemary. My neighbours used to take bits of rosemary for the barbecue or their Sunday roast lamb and perhaps they hadn't noticed that the rosemary was gone and this strange new 'rosemary', with red flowers, had taken its place. If so, they must have given it a hell of a yank, as I'd planted it quite firmly. Grevillea is a lot more prickly than rosemary, so if that's the case, I hope it bit them back.