An email from the consultant to the operator’s then western Mediterranean director was revealed on the second day of the hearing, which began this week at the Royal Courts of Justice in London.

The email, sent the day after the March 2015 attack on the Bardo museum in Tunis, referred to a translation of an Al-Qaeda YouTube video threatening action in Tunisia.

The transcription read: “We are going to expand to Tunisia whether you like it or not.”

The film prompted the consultant to warn Tui: “I would suggest that today’s incident is the start of an active campaign within Tunisia.”

The Sousse killings took place in June 2015 and the inquests revealed that before this, a UK Foreign Office (FCO) “recce” had been carried out in Sousse and Port El Kantaoui to examine access and security at 30 hotels after a failed suicide bomb attack at Sousse’s Riadh Palms Hotel in 2013.

Counsel for 20 of the 2015 victims, Andrew Ritchie QC, said the visit, led by an unnamed expert, had included the Riu Imperial Marhaba hotel where the massacre took place.

“His conclusion was that despite some good secure infrastructure in and around hotels and resorts, there seemed little in the way of effective security to prevent or respond to an attack,” said Ritchie.

He also said some victims had been told by Tui agents when booking that the Bardo attack was a “one off” and that Tunisia was “100% safe”.

The hearing was told that operators and the FCO expected hotels to raise their own levels of security in line with the increased threat.

Ritchie told the inquests there was however a reluctance by Tunisian authorities to increase police presence generally. The hearing was told that before the 2010 revolution the country had been run as a police state for 23 years under president Ben Ali, and the new government did not want to return to this scenario.

The inquests also examined correspondence between the then British ambassador to Tunisia, Hamish Cowell, and FCO officials in the wake of the Bardo attack.

The letter spoke of an increased risk to Britons proportionally because of record tourist numbers to Tunisia, fuelled by low prices.

In May 2015, UK visitor numbers were up 61%, it said, while French tourists were down 65% and Germany holidaymakers down 24%.

The inquests continue and are expected to last seven weeks.