Thanks lads, I'm humbled really as I realy don't consider myself a \modeller\ yet
Cheers Thump - I've been using single and double rows of 4 3x3x3 cubes myself - good to know I'm on the right track I've found even a single row works very reliably, but the uncoupling 'window' is very short (which can be a good thing). For points that I can't easily see, I'll use double or triple row (for loco release locations especially).