At least you considered it, which is more than many do in the same position.

Back to the optical switches, the basic mechanical ones are very flakey. They're made for pennies and sold for pounds so you can guess that the optical quality of the internal components isn't that great, nor is the physical alignment. That's why so many get returned. It really is luck of the draw with them. The Lindy that Chris mentioned is a better brand without breaking the bank. Go with that. Good luck.

So just to let you know I am now all sorted thanks to you guys on here. I took back the tacky plastic optical switch to maplins for a refund. (Although the chap in marlins claimed the problem was with my sky box and not with the switch but eventually agreed to a refund!) I ordered the Lindy product from Amazon which arrived today. Now connected it up to HC system, Sky Box and Apple tv and all working great. In fact Im sure the sound is even better now! Thanks again for all the help.