An inquest is due to open into the deaths of four men killed when a helicopter in which they were travelling crashed during take-off in March 2014.

Businessman Lord Ballyedmond, 70, and his employee Declan Small, 42, from Mayobridge, County Down. died in the incident at Gillingham Hall, Norfolk, along with the 36-year-old pilot Carl Dickerson and 45-year-old co-pilot Lee Hoyle.

The coroner's inquest is due to begin in Norwich tomorrow.

Lord Ballyedmond was the chairman and founder of the international pharmaceutical company, Norbrook Laboratories Ltd, based in Northern Ireland, and a member of the House of Lords since 2004.

He had also been a senator in the Irish Parliament from 1994 to 2002, and was prominent in the peace and reconciliation process in Northern Ireland.

An air safety report into the crash was published by the Air Accident Investigation Branch (AAIB) in October 2015.

The investigation said the take-off Lord Ballyedmond's estate, Gillingham Hall would not have been allowed in such conditions from a licensed aerodrome.

In a pre-flight conversation between two pilots in the helicopter, one of them said he was not 'very happy about lifting out of here'.

The report said the flight crew lacked external visual cues, formal training and procedures to fly in the conditions.

The AgustaWestland AW139 was due to depart at 6.30pm on March 13 but the two passengers were not ready to leave until 7.20pm.

By the time the crew were ready to leave, a 'dense fog had set in' which witnesses said cut visibility down to 'the order of tens of metres'.

The AAIB examined the contents of the cockpit voice and flight data recorder, which recorded the pilots discussing the conditions.

The helicopter reached an altitude of 82ft and a ground speed of 90 knots before it crashed nose-down into the field.

The report said it hit a line of large hay bales lying across a field, which destroyed the cabin structure.

The inquest will examine the circumstances of the crash, and consider any recommendations.