Thanks everyone for the thoughts on that.. a couple of...

Thanks everyone for the thoughts on that.. a couple of interesting responses which cover the Buy side or the Sell side reasonings..

1) Just to add.. if a Seller was workong to an agreed price after auction, then could not they have co operated at a lower price if they have both sides of the buy and sell.. or
2) If an institution was Buying then to wait to the end of the day doesnt seem to make sense.. they could have started buying at the low 5.20s for most of the afternoon

I welcome any other thoughts.. it was a good surprise but it will be interesting to see if this spike is supported on Open..