I really don't think you should be so judgemental about the son. I am afraid you can have no idea what he is or isn't doing to help his mother and it appears there are already carers going in who will know a great deal more about the position than you do.
It is really of no consequence if her son lives in a "VERY posh house in a VERY nice village". Or how many times he visits. It sounds as if her has Power of Attorney and if so that implies some loss of capacity as does the fact that she cannot cook her own meal. Being the main support to anyone is something you can only get wrong however much you try to get it right and it sounds as if she may well have some form of dementia. People with dementia are, as one of my mother's carer once commented, very convincing. This is because they believe what they are telling you but that does not make it true.
Over Christmas I had a call from some friends of my mothers - neighbours from long ago, as she had thanked them for the flowers they sent her when they rang. They had actually sent her a cardigan. The very kind friend said they had noticed she "gets a little muddled" and seemed very shocked when I explained that she had been diagnosed with dementia five years ago. Mum has managed very well and she has always been a kind person but it has not stopped her complaining to a neighbour that I was trying to put her in a home - the complete opposite of what we have been doing. I also don't let mum have too much cash as, as well as squirrelling it away someone could take it from her - she wouldn't really be able to work out what should be paid - or she might well forget to pay someone or pay the wrong amount as the value of money has now disappeared so most of her bills are paid directly by me from her bank account including the Wiltshire Farm Foods frozen meals which have allowed her to stay in her home and care for herself up 'till now.
You say she used to be very tidy - so did my mother. She still has her hair done each week but sometimes she has dinner down her cardigan. It is extremely difficult to get her to let me do her washing as she believes she still can. I used to insist on finding her a clean one and then just taking the other away but it is verging on cruel and who cares but me and the outside world. To be honest I would rather she wasn't made anxious and I can scoop things up often enough to take them and wash them so that we stay on the right side of not brilliant but OK. It is hugely difficult and he is almost certainly doing the best he can even if it is not what you believe you would do in the same circumstances.
You ask what you can do. Firstly, your concern is with your father. It sounds as if these are local authority houses so it may be worth contacting them - they may decide to put in more care which would probably help. Otherwise you could ask the son if there is anything you can do to help. If you don't want to do that then I suggest you leave well alone other than, as I said, taking responsibility for your father.
