Late afternoon

After a very frustrating day l took myself off for a walk around some water the nearest being the little lake at Ally Pally park.  I was most surprised to see it was still frozen solid.  All the birds seemed quite strangely agitated and l was wondering why, surely not because of the ice and then l heard (but did not see) a sound - a hawk screeching.  There must have been a Sparrowhawk or some kind of bird of prey about.  It was getting dark and was bitterly cold l came home.