What should we do?

Would his car be in his garage? Could you shout through the letterbox? Would he usually say if he was going off on holiday? Bit of a worry.

I would call the police for advice.

They must be used to this kind of situation and can decide what needs to be done.

No, he wouldn't tell us if he was going away.
If he is away, I'm going to make sure he knows that he must tell us next time!
His garage is in a block at the back of his house but what a good idea to check it. Will do it now. Thank you!

I think the car is the key here. If it's gone then so is he. But if in a garage then that's difficult. However, you can't really call the Police and break into his home or garage for no real reason, as he may just have gone away. Do whatever you can from outside the property and maybe try contacting the local U3A to see if anyone knows more. If and when he returns I would have a conversation about this, as he needs to understand he could have a fall and be unable to call for help. Try and get either his or the daughter's mobile number.

Just knock on the door, if you don't get a reply then knock again at a different time.

Some good hefty knocks on the door or ring his doorbell a few times. I hope he's alright.

I did this not long ago at a neighbour's house because I hadn't seen him over the weekend and his car hadn't moved.
As it happened he'd just felt a bit off-colour so had stayed indoors. I was bothered because he'd had a heart attack last year but luckily he was okay.

If you look up the local U3A site on the internet and look up the bridge group there will be a contact number for the leader and you could contact them perhaps if you continue to be worried.

Check on the car situation first. If it's in the garage then perhaps call the police to ask their advice on what to do next.

I've once done this, when I noticed an elderly neighbour's gas fire was on late at night and then still burning away the next morning. I don't recall whether I called the police or someone who knew her, but it turned out she'd stayed overnight at her daughter's house and had just forgotten to turn off the fire.

Hmmm.....can't see into his garage.
He is the leader of the U3A Bridge group and we have his phone number but, of course, there's no reply.

My feeling is that he's just gone away, not thinking that he needed to tell someone but I'm just worried that he's collapsed.
I can see his lounge and bedroom and he's definitely not there, can't see his kitchen, bathroom or garden.
If he comes home, we're definitely having that conversation. I know he'll laugh (and be secretly delighted) that I've been so worried.

Mail behind door? Can you get a ladder on climb up to see over into garden? Or can you see in from other neighbour’s garden.

My Dad used to do this, he'd get a thought to go off for the day or several days and just go. He knew he was OK and it didn't occur to him that we/anyone would be worried. Hopefully that's what has happened to your neighbour. When he turns up, hail and hearty, it might be an idea to get to know him a bit better and yes, gently suggest it's sensible to let someone know when he will be away if for no other reason so you can keep an eye out for his home. He's lucky to have a good neighbour.

Call the police. They will be used to queries like yours.

Better safe than sorry.

Beejo, you say that he's fiercely independent. He will view you as a nosy neighbour and he doesn't have to let you know if he's going away. I wouldn't tell a neighbour either, as there are so many burglaries around here.

However, the woman opposite is a terrible worrier who lives on her nerves. Therefore, I've let her have my daughter's mobile number so that she can send a text and be reassured if she has concerns. I also have her number and I let her know if her house alarm goes off (which it quite frequently does). She gets me a small Christmas gift as a thanks for the watchdog duty!

I know this sounds grim but can you open the letter box flap and sniff?
If you haven't seen him for a few days and he has collapsed or even died, there will be a distinct odour.

And if his windows are on vents, that gives access to flies, which will buzz.

If you smell only normal household aromas, chances are he's away.

I'm sorry if that sounds horrible.

I had the same problem with my neighbour who went to see family in Australia and told no one.

We did have a local official with a key who let us in but it took just a moment to see he wasn't there.
Now he always tells me.

We don't have letterbox flaps like they do in the UK, only outside mailboxes a la US.

Thanks everyone. We've just found out that our neighbour has gone to visit a son we didn't even know he had!
After questioning other neighbours, peering through his windows and over the garden wall, we contacted the U3A who rang someone, who rang someone in his bridge group, who passed on the information.
We feel better because everyone who knows him, knows how uncommunicative he is.
However he does know that I worry about him and a number of years ago told me to look for milk bottles not taken in from his doorstep - fine, but, of course, no-one delivers milk any more.
We shall be having words when he returns!

He is lucky to have such a caring neighbour.

Glad your mind has been put at rest.

Glad that had a happy ending and yes, as others have said, he's lucky to have a caring neighbour like you.

Thank goodness for that.

That’s good news. Yes, have that chat when he’s back. We used to flit off without telling anyone (shades of my Dad) but stopped when we realised how much people worried.