A fuller account is given at the excellent West End at War website:
The first photo was taken from Oxford Street in 1939 and is looking west towards Marble Arch. The road behind the bus is Holles Street and this divided the two shops that made up John Lewis's - the store on the left with the dome was called the West House and the building on the near corner was the East House. Holles Street runs up to Cavendish Square.
The second photo shows a similar view, but from roughly four floors up, shortly after the bombing. Two hosepipes are being played on the wreckage from Oxford Street on the left but it is evident the main damage in the West House was around the corner with the façade a pile of rubble in Holles Street and the inside of the building entirely gutted.
The third photo seems to be taken at a similar time to the one above, with firemen still working and smoke still rising within West House. Their attention is on the East House, which had been affected by fire spreading from the West House in the night.
The fourth photo seems to have been taken some time later because the firemen have now left but the rubble in Holles Street was not yet clear. The photo also reveals that much of the rear of the building on Cavendish Square seemed to have survived.
As the account on the West End at War website makes clear, three firemen were feared killed when a bomb exploded nearby; however, an eyewitness was reported to have seen them getting in a taxi.
Inspection of the list of civilian war dead held by Commonwealth War Graves Commission (CWGC) shows two firemen died that night, named Harold Gillard and Donald Mackenzie.
Harold Colenso Gillard was born in early 1900, the son of a plumber, John, and Rosa, and lived at 77 East Street in Marylebone (parallel to Baker Street). There were seven children in all, the oldest four being boys (Harold was third) and the youngest three being girls.
His unusual middle name, Colenso, was a battle in the 2nd Boer War (15th December 1899). One source says this was because his father fought there, but as John was a 38-year old plumber at the time, this seems unlikely. Another possibility is that while the battle was a British defeat, there was considerable publicity for four soldiers awarded the Victoria Cross for saving two artillery guns under fire; the citation in the London Gazette appeared on 2nd February 1900 and may have inspired John and Rose to name their new baby. (Perhaps the same patriotism inspired 40-year old Harold to volunteer for the AFS?)
East Street was re-named Chiltern Street around this time, and today the house looks like this (the bigger white building on the right is the Park Plaza Sherlock Holmes Hotel):
One family lived on each floor, including the basement. While they moved to different premises, times must have been hard, and then John, his father died, in 1914. We then lose sight of the family, until 1924 when the electoral roll has him living at 81 East Street, immediately next the hotel in the photo above; his mother and younger brother also lived there and younger siblings not yet eligible to vote may have lived with them. We do not know what Harold did for a living, but his older brother had started worker at a decorators, so it is possible he followed his father into some branch of the building trade.
Harold seems to have married in 1926, to Nellie Hodgkins, but his wife does not appear at the same address until 1928. Almost every year sees a change of address and people resident there; his wife is last mentioned in 1932 and in 1936 he married again, to Mildred Chambers. He left East Street in 1938 to live in Lisson Grove with his wife, at 32 Portman Buildings:
Harold's mother died in 1947, his second wife in 1967.
Donald was born around 1907 to Duncan, a tailor from Inverness-shire, and Rebecca, a farmer's daughter from Norfolk. His parents were comparatively old when he was born (51 and 39), yet he also had two younger sisters.
In 1911, the family lived at 44 New Cavendish Street where Duncan worked from home, but then they slip from view and the electoral roll next shows Duncan in 1929 living not far away, at 14 Marylebone Street, with his mother (seemingly widowed). He still lived there in 1940, still with his mother, but with a revolving cast of siblings and other relatives.
We do not know what he did for a living but he may have followed his father as a tailor.
It's striking that Harold and Duncan both lost their fathers when fairly young and were living with their widowed mothers for years after - we can only speculate what effect this had on Harold's first marriage. Both men were living within a stone's throw of where they were born, local boys who would have known the streets on the way to the fire.
We can only speculate whether they were part of the same Auxiliary Fire Service crew, but the balance of probabilities is that they were (they came from the same area and are likely to have been working close together when the bomb exploded). We do not know what their experiences had been over the past week - had they been to fight fires in the docks? how tired were they? - and we do not know why they were sent to this incident rather than the fire in Great Portland Street or the bomb that had exploded at Marble Arch Tube.
So much is unknown.