There's quite a bit of Arnhem related activity on Twitter at the moment on the provenance of this photo. The following is a thread based on it.

An alternative school of thought to that going around at present is that the man on the left who is holding the Sten Gun was Private John Dugdale of 10 Platoon, C Coy, 156 Parachute Battalion.

The man behind him holding the pistol is believed to be L/Cpl Noel Rosenberg MM, again of 10 Platoon, C Coy, 156 Battalion. Rosenberg was recommended for the DCM but this was downgraded. His citation read "During the entire action at Arnhem this NCO was an example to all around..

..him for his exhibition of coolness and courage under fire. On numerous occasions he volunteered to carry messages under fire; he personally killed a large number of the enemy at different times and whenever circumstances were serious he would be heard encouraging & steadying..

..those around him. He was particularly conspicuous on the 20 Sep '44 when the remnants of the Brigade were surrounded by the enemy in a hollow in the woods, standing up in full view of the enemy in the face of intense fire to direct the fire of other men on the enemy positions."

Noel Ross.

The solitary rearguard mentioned at the end of the citation occurred at a feature now known as Hackett Hollow. This was held by the remnants of Shan Hackett's 4th Parachute Brigade HQ and C Coy of 156 Parachute Battalion under Major Geoffrey Powell MC.

Another of those present at the Hollow was Lt. The Honourable Piers St Aubyn MC, who low on ammunition resorted to urging the surrounding Germans "using a mixture of hand signals and choice Anglo-Saxon to put down their arms and fuck off"

Following the breakout from the Hollow the remnants of C Coy, 156 Battalion were sent in to the defence of the perimeter along Paul Krugerstraat in Oosterbeek.

On 22 September 1944, Geoffrey Powell sent St Aubyn to go to Brigade HQ, just a few hundreds yards east of Divisional HQ at the Hartenstein Hotel for orders and any rations that may have been available. Aubyn took an escort of 4 men from his Platoon, including Dugdale & Rosenberg

The photo was taken in the roofless Orangery close by 4th Parachute Brigade HQ on 22 September by Mike Lewis of the Army Film and Photographic Unit. This was within the Oosterbeek Defensive Perimeter and was a staged photo.

One of those who witnessed the picture being taken was Captain Harry Faulkner-Brown of 4th Parachute Squadron, Royal Engineers. Faulkner-Brown had just been brought back from the northern line of the Perimeter at this point of
Graaf van Rechterenweg with his men to rest.

In his superb memoir, 'A Sapper at Arnhem' Harry wrote of the incident on 22 Sept "About the middle of the morning a group of about four members of our Division appeared with a press photographer, who proceeded to take shots of the group moving through the ruined garages [sic]...

...After everything we had been through we were rather disgusted at this untrue, artificial display of house clearance, and my sappers gave them a few boos and cat calls as an indication of their disapproval."

In my opinion, for what that's worth, I believe Faulkner-Brown's comments help explain why it's never been completely established exactly who was in the photo. There will always be claim and counterclaim (and there have been dozens) but of all the photos...

...taken during the battle this is the one that gains the most attention despite being one of the least deserving.

For further reading here are two of the best books written about the Battle of Arnhem by the authority on the 156 Parachute Battalion, John O'Reilly. They aren't cheap but as ever with these things, you get what you pay for.