Thank you James/Peter, I do like the idea of breaking 2 beams simultaneously before alarm activation.
I have just had a quick look at the link, seem those twin beams will have to see each other for it to work, right?
My car is park directly in front of the garage, being a numpty, am I right in thinking that I would have to install a pole somewhere along my drive for it to work?
But it would be quite unsightly, I want something a little more discrete. Or have I missed something?