Having read all the above discussion, I'm still at a loss to understand why the CAA advocate a square circuit for light aircraft. While I realise that it is the status quo and would conform to such a pattern in a busy circuit at a civil airfield, I cannot see it's advantages over a military oval pattern. The downwind leg really needs only to be long enough to complete pre-landing checks and ensure that you know the position of other circuit traffic, and an oval circuit can accomodate quite a few aircraft if so desired. After the finals turn is completed there is still plenty enough time to stabilise the approach and prepare for landing. In addition, tight oval circuits would ensure that circuit traffic is afforded the full protection of the ATZ. I would therefore argue that the CAA should advocate an oval circuit. They won't of course!