West residents hoping to solve one of the region's most tragic mysteries have been offering their memories of the Charfield rail crash.

Next month will mark the 80th anniversary of the disaster that killed 15 people.

In the early hours of Saturday, October 13, 1928, the Leeds to Bristol night mail train crashed under the road bridge at Charfield station, South Gloucestershire. Gas cylinders used to light the carriages blew up, and the fire was so savage that 12 of the people who died were so badly decomposed that their relatives accepted the railway company's offer of a mass grave, which is still prominent in a corner of the village churchyard.

On the memorial stone, the mystery lives on. After listing 10 names it ends with "Two Unknown".

The bodies were never claimed or identified. Down the years, folklore and legend has built about who they were. One theory is that two ventriloquist's dummies had been aboard, another that a jockey had been mistaken for a schoolboy, but most residents believe the bodies to be those of children.

Tony Williams, 69, from Wiltshire, said: "My father-in-law, Eddie Clark worked in a brickyard in Charfield. He told me that at the time of the crash people came running to his house for help and he remembered the remains of the two unknowns. He said they were definitely the bodies of children."

Gordon Tartaglia, 57, from Cheltenham said: "My mother was evacuated down to Charfield during the war, because she had family there. She used to work at the railway station with her grandfather. At the time of the crash she said the strongest rumours circulating were that the children were royalty, illegitimate royalty that is, but that is the reason why it was all hushed up."

Villagers remember a lady in black arriving every anniversary from 1929 to the 1950s to stand silently by the grave. Mr Tartaglia said: "The dark-clothed woman who visited the graves was also presumed to be royalty. Of course, there is no way to back this up, but it is an interesting twist."

Mrs Curwood, 90, from Chard, said she was living in Charfield at the time of the crash. "I was only 10 years old at the time. I remember as if it was yesterday. I was lying in bed and heard this massive bang. I dashed across the landing, but my father told us to stay where we were. Mr Button, the signal man, lived near us you see, so my father went out to help.

"It was such a tragedy and nobody questioned the lady in black – that was how people lived in those days, not like today when everyone would have asked who she was."

Local author Hazel Peel adds another layer to the mystery in Glorious Gloucestershire. She said: "I found that in 1937 in a totally unrelated court case a female called Alice Mary Desborough claimed she had been a passenger on the ill-fated express and that the two unknown small bodies were indeed those of children and they had belonged to her brother. If that is so, why had she taken so many years to speak out?"