Thanks folks, the overwhelming consensus seems to be 5 for the boys!
I started myself at 4 and a half but sure then again it was the 70's so it was wither school or sit and watch yer woman doing x's and o's on BBC2 all day..
I started at just over 4 and a half - I would have been sent the year before but I was still 3.
Lord ye were posh with bbc. We only had rte 1 and 2. I was 7ish before I knew what colour boscos hair was, it being when we got a colour tv and afraid of our lives we'd go blind from watching it.