Can anyone throw any light on this?

I wouldn't worry. I've accidentally taken photos of all sorts of things with my phone. Usually my feet, the cat or once even my shopping trolley . My problem is long fingernails - not always accurate with my phone.

Do you have one button on your phone that's set up to take a photo? That might be the cause.

I would guess the same as Primrose

Have your GCs had access to the phone? Even very young ones can work them these days. GD aged 2 wiped everything from her mum's iPhone in a couple of minutes (no-one is sure how) so 1 little photo would be a doddle. 2year old GS can now use the torch function on mine and sometimes shuts off my wi fi!

I wondered that, but it doesn't look like an accidental photo. (Even the photos that DH takes deliberately tend to look accidental!). It looks posed and quite close up. His phone also has a cover that folds across the screen, with a magnetic clip, so unless he has it open and activates the phone function, it wouldn't take accidental photos. He has to touch the screen to take a photo. .

Intriguing! But as you've deleted the photo, all you can do is speculate...

Before you zapped it, did you notice the date and time the photo was taken? That could pinpoint where you were and possibly jog your memory abut what was happening. Youi might have seen what was in the background, Maybe the phone was on a table for a few minutes and some comedian someone picked it up and shot a selfie?

Did he accidentally take a screen shot of something he was looking at on line?

I bet he flicked it whilst doing something else I ve fond it before now but if you ve deleted it you ll never know

Well ... could it be something like this: I was at a supermarket Photo Booth a year or so ago, and the assistant was helping me to send photographs to the photoprint machine via the ether. The next thing a message came up on my phone "Image successfully sent to XXXX" (a strange phone number). I said "What the Hades...!?" And he replied something to the effect that if someone walked past at the precise moment that I had pressed "Send" and had a live/open BluRay signal on their phone, the photograph could have gone to a stranger's phone!

It certainly hadn't gone to the printer. I was out of there like a shot, sans print of photo, and have never been back.

I've noticed recently on my Samsung phone that in my library I have pictures that I didn't take but were in folders named Facebook, Google maps , Messages etc and it seems a recent update of the software ( or a setting change) now means im picking up pictures from previously unaccessed places.

Perhaps this is the same ?

I was just thinking I ought to get myself a smart phone.
Changed my mind now.

Goodness, anyone would think there was some supernatural activity going on! Delete and/or run away seems to be the usual reponse...

Elegran no, unfortunately he deleted it very quickly or that would have been a good idea. The subject was sitting in a car, with his arm resting on the open window, looking straight into the camera. There wasn't room for anything in the background. As it isn't an iPhone and we don't have a computer, it isn't a simple matter to retrieve the photo.

I hope not shysal; it would have to have been "find a drug dealer" by the look of this guy! (Yes I know - judgemental - he could have been a plumber having a bad day for all I know). He didn't look very friendly.
When my SGS's come down on Sunday we will ask them if they have any ideas; or know any drug dealers; or plumbers. I did read that odd images can be transferred from Whatsapp onto a phone, but he doesn't have it. It isn't an Apple phone.

Just caught up! Crikey!

It is possible to pick up other people's phone messages etc on your phone. I did a course on Cybersecurity with Futurelearn and it showed you how your Facebook page etc can be seen by others in the vicinity with the right phone. It has made me a lot more careful about using it on trains etc. I wouldn't worry too much about it though. he probably didn't know it had been sent to you.

Just love technology. I had a new ipad last year and when I was setting it up it decided to connect to the main pc and was just starting downloading the photos from there. Seems OK except there are nearly 20,000 there (mainly work). I managed to change the settings before the memory was full.

Greyduster you should be able to find deleted photos on your phone, they probably stay there in a separate folder until your memory is getting full.

He doesn't have Facebook (I do) but he does spend a lot of time on Twitter. I have looked at his phone and can't seem to find a folder for deleted photographs. Online it just tells you to link the memory card to a computer to retrieve any deleted items but we don't have one. We are probably getting jumpy for nothing.

Funnily enough a few years ago my sister found some very questionable photos of "men's bits" in her photo gallery on a Samsung phone . We had been to a concert the previous night and she definitely didn't take them . One of our techy guys at work said it is possible to Bluetooth them from one (same) phone to the other . She had been taking photos at the concert and we wondered if someone had noticed the same phone as theirs ? Not sure if this is possible really ? But can't think of any other logical explanation.
Oh btw neither of recognised the "bits"

I have had 2 incidences of this. One was a picture of a little girl that none of us knew but came from my daughters phone.
The other was a picture of a man on my iPad. The odd part of that one was, was that this mans picture was between pictures that the grandchildren were taking at the time.

A bit puzzling but there will be a logical answer.
Even very small children can operate phones, when GD2 was two years old she took a selfie and sent it to my sister. She could not read so it was pure chance that she picked up on the one number on my phone which was most frequently used. We still laugh about it because I still have not mastered sending photos.

The only other way to get a picture onto your phone that I'm aware of is via Bluetooth (It's also called Android Beam). If you have it switched on, it's possible to send photos to other phones close by or to receive them. It may be that someone has chosen your phone by mistake. It's not unusual for several people nearby to all have a Samsung, or an iPhone so it could be that they've simply chosen the wrong phone to send the photo to.
If you use things like bluetooth headsets etc, it's not unusual to have it switched on all the time.

Could it be a 'sample' shot? Some devices come pre-loaded with a file of sample images in the Gallery. I've never been sure why and tend to delete them if possible

The trouble with smartphones is that they're smarter than me. Every time I think I've caught up they're off again with features that I have no clue about. I probably use about 20% of what my phone could do.