Puzzle

I took my visitor from New Zealand for a walk in the park after the rain had stopped. As we got to the lake she noticed this bird at the edge of the lake. We spent some time watching it aswe could not work out what it was . I had never seen anything like it in the park before. We asked a passer-bye but no help there. As we moved further along we saw it from a different angle. Then it stretched its neck a little and we could also see its legs. We think it might be a heron?