Unfortunately, in my experience, help can only be triggered by one of two things. Firstly the person has to request it. The LAs usually will make a telephone call to the person concerned after they have been made aware of the situation by a relative. If the person refuses to co-operate they will not interfere, saying that the person has a right to choose.
The other way is for a 'crisis point' to be reached. Usually an accident, a fall, hospital admission or the person deemed to be a danger to themselves or others.
I would email the his Local Authority Elderly Persons Unit, outlying your concerns. That will start a file on him but are unlikely to visit him unless he agrees.
On a practical note, start to make a file of all his details. apply for PoA if he is agreeable, and try to get him to allow you to add your name to his bank account. If you visit and if he is agreeable, collect up as many papers as you possibly can.
Make lists of all his accounts, utility bills, phone numbers of GP details, hospital appointments and medications. Every time you make a call on his behalf, log the date time, name of who you spoke to and the outcome. Nothing you do for an elderly person ever gets resolved with one phone call, so having the log gives you ammunition in getting through red tape. The PoA will allow you to have his mail redirected to you, something I have found invaluable.
On the front of the file write, his full name, DoB, and place of birth. Date of marriage, Date you mum died. National Insurance number, his address and postcode. GP address and tele. Number. Any time you are asked for info not on the file add it to it.
You will be surprised how many times you have to give the same info, to the same organisation. Quite often the sheer frustration makes your brain freeze, but having the info to hand does speed up things.
Sorry for the essay