Question Author
Mrs.chappie,
I now think it died of a broken heart, as we have seen a dead swan by a railway track just half a mile away some weeks ago, and its partner was hanging around ( it was killed by a car on the railway crossing) for several days, and they mate for life, and we have seen this poor swan many times in that area, and we saw a lone swan a few days ago on our part of the river, so assume it was him ( or her) sad, but the good thing this year is that the water board let the water back into the river ( really a very wide drainage channel) early, before the swans started nesting, so they are on high ground, unlike other years when the swans nested, then the water rose and killed the cygnets or washed the eggs and nest away. not good.
Percy.