Read a book about the man who owned the Shiant Islands some years ago, and I think that they featured on a TV program too. The columnar basalt is very distinctive, and is not that common. Fingal's Cave and Kilt Rock are the most well known examples, but it didn't look like them. There's also an outcrop on the south side of Arthur's Seat.
No idea exactly which island though - I could go trawling through loads of photos online to find out - but I'm not going to.