Luton Crown Court heard how Simon Thomerson, the sole owner and director of Clearview Design and Construction Ltd, had been contracted by the owners of an industrial park in Hoddesdon, Hertfordshire to refurbish several of the units.

Brothers Ardian and Jashar Lamallari had been employed as labourers and were working inside the unit on 3 October 2015 when an explosive fire occurred within one of the units.

Both brothers suffered near 100% burns and died within 12 hours of the incident.

A third man who was working with them also suffered severe burns, but survived.

A joint investigation by Hertfordshire Constabulary and the HSE found that Thomerson had supplied the three men with several litres of highly flammable “thinners”, which they then poured onto the floor of the unit to remove old dried carpet tile adhesive.

The investigation found that Thomerson had given no serious consideration to the safe use of the thinners, despite the obvious warnings on the containers.

The vapour spread over an area up to half the size of a tennis court and was ignited by one of several possible ignition sources that were in the area.

Thomerson of Sutherland Avenue, London, pleaded guilty to safety breaches and received a custodial sentence of eight months and was ordered to pay a victim surcharge of £170.

Detective Inspector Justine Jenkins from the Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit who led the investigation said: “This was a tragic event that led to the death of two men in absolutely horrific circumstances.

“We have worked closely with HSE and our other partner agencies to ensure that the failings by those in control of the site were identified and prosecuted and are satisfied that the sentence delivered today reflects the seriousness of those failings.”

Speaking after the hearing, HSE inspector Paul Hoskins said: “This tragic incident led to the wholly avoidable death of two brothers, Ardian and Jashar, destroying the lives of their young families.

“The risks of using highly flammable liquids are well known, and employers should make sure they properly assess the risks from such substances, and use safer alternatives where possible.

“Where the use of flammable solvents is unavoidable, then the method and environment must be strictly controlled to prevent any ignition.”

In a victim impact statement, Zana Lamallari, wife of Jashar said: “After the death of my husband, my family life has completely been destroyed. My children’s and my future has been completely destroyed. He was everything to me.”

In a victim impact statement, Ismete Lamallari, wife of Ardian said: “The impact in my life is so big. My family has been destroyed; my home, everything. My husband was very loving towards the children and everyone. He was an honest worker.”