I'm not sure if Blundstone manufacture half sizes but, even if they do, they are not imported in to the UK. So a size 7 arrived and was, unsurprisingly, too big. However, the seller was extremely co-operative and, despite being out of stock of the size 6 variant, I had it with me within a week.
As for the size 6 - I've been wearing them for a couple of days now and they are quite impressive (if easing a little from being slightly tight). More sturdily built than the couple of pairs of (significantly more expensive) RM Williams dress boots I've had for a while now and with a more robust sole type - but don't expect Vibram equivalence. With the non-polish finish, significantly less dressy. A good day-to-day wearing Chelsea boot, if your days aren't spent in suit and tie.