Yeah, as the Railscot page mentions, the line that runs through Giffen comes off of the Glasgow-Kilmarnock line at Lugton and goes to the MOD Base at Beith (though formerly the line also continued down to Kilwinning and beyond).
Just south of the station's remains, where the line curves heading in the base, is completely overgrown.
Photo by Chris Court
I'd say there hasn't been a train down this track in at least a decade. The rest of the line from Giffen to Lugton is mainly intact, though there are some light weeds in places.
Interestingly, the line has seem some use in the last decade, for some kind of training exercise
after the Paddington rail incident. This probably took place closer to the main line than Giffen.
Probably more info than you wanted to know! Basically, it's now a 2-3 mile stretch of track that goes nowhere. I'm not even sure who owns it, there's a modern looking sign on the track at Giffen that says "private locomotives beyond this point only", so the MOD probably own part of it. I tried asking the British Rail Board as I was wanting to shoot a film down there at one point, but they never got back to me.
Incidently, does anyone know of any other locations like this, with old track still running through an abandoned station?