The shocking cause of the gas explosion that rocked Rackheath Industrial Estate in January 2011 has finally been revealed.

More than 18 months after the explosion completely destroyed a small cafe on the estate, north of Norwich, Broadland District Council has released the findings of an in-depth investigation.

It has been decided that no criminal prosecution will be brought, in light of the report revealing the several calamitous mistakes that so fortunately did not lead to any casualties.

The report states:

- The cafe's new leaseholder had not realised the gas cylinders which caused the explosion were no longer connected to its gas oven.

- A worker for an unnamed 'reputable national' gas supplier then failed to realise the cylinders were not connected to the oven either and arranged a delivery.

- The subsequent delivery at around 1pm on Wednesday, January 12, 2011 saw the cylinders refilled and its valves opened, filling the cafe with gas.

- The cafe's leaseholder had smelt gas when closing for the day.

- Nine hours later a 'major explosion' destroyed the cafe and caused 'considerable damage' to many other business units on the industrial estate.

The investigation was lead by Broadland District Council, in liaison with the Health and Safety Executive (HSE), Norfolk Fire and Rescue Service, CNC Building Control Consultancy and a specialist investigator.

Following the publishing of the report, Broadland's portfolio folder for environmental excellence, John Fisher, said: 'After careful consideration of the council's enforcement policy, the available evidence, legal advice and guidance, our joint priority with the Health and Safety Executive, was to discover what happened and take the measures most likely to prevent something similar happening again.

'We concluded that a prosecution was not appropriate in this case.

'Instead, the Health and Safety Executive has advised the gas supply company to review its procedures. We are also supporting their efforts to ensure that tighter codes of practice and guidance are developed nationally to deal with safety issues which affect the industry as a whole.'

Items were recovered from the blast site, in Wendover Road, and sent to a specialist laboratory in Buxton, Derbyshire, for detailed expert examination.

Various people were interviewed for the report, including the leaseholder of the cafe, and an HSE officer interviewed representatives of the unnamed liquified petroleum gas (LPG) supplier.

The report states that the previous leaseholder of the cafe had LPG (propane, in this case) powered equipment, including a cooking range installed within the kitchen.

This included a gas oven with a six-ring gas hob, supplied by two 47kg cylinders, located in an external metal security cage.

However, at some time prior to the explosion all the LPG fuelled equipment had been removed from the kitchen.

The external LPG cylinders and accompanying equipment were not removed when the lease was sold on Christmas Eve 2010 though.

The report states: 'The leaseholder at the time of the explosion was of the incorrect view that certain kitchen appliances included in the sale of the business were LPG fuelled.

'The leaseholder became concerned that LPG supplies might be running low. Therefore, the leaseholder resolved to contact a business they believed to be a recognised reputable LPG supply company to visit the premises to arrange a supply of LPG.

'On Monday, January 10, 2011 a representative from the supplier visited the premises, assessed the potential LPG requirement, arranged a contact and a subsequent delivery.

'At approximately 1pm on Wednesday, January 12, 2011 a delivery driver from the same LPG supplier called at the premises.

'During the delivery routine, the driver manually adjusted the automatic changeover valve, disconnected and removed an empty or almost empty cylinder from the security cage and installed a full 47kg cylinder. The driver then opened the control valve on the cylinder.

'Shortly after the delivery the leaseholder noticed a smell of gas in the cafe. The leaseholder carried out some checks but was unable to identify any problems or ascertain the source.

'However, at the end of the working day at approximately 3pm the leaseholder closed and locked the premises and departed for home having not resolved the source of the smell of gas.

'At approximately 9.10pm there was a major explosion.'

That explosion caused chaos on the estate for the next couple of days, although it also saw people involved with various businesses work together to get the site back towards some form of normality by Friday lunchtime.

The report brings to a close a long wait for answers but also makes it clear just how fortunate it was that the explosion happened at night, when the industrial estate was largely empty.

- Have you got a story for the Evening News? Contact reporter David Freezer on 01603 772418 or david.freezer@archant.co.uk