They had just enjoyed a light lunch when the Training and Development Agency for Schools co-ordinator stood up to read a prepared statement: the workshop was off, they could all go home.
"The reaction was stunned and shocked," said one of the attenders. "People had set aside two days to be there. Most people put it down to Department for Education and Skills incompetence."
The same scene was occurring in Wolverhampton, Bristol and Chester. Another 12 courses, scheduled for this week and last, with hundreds of attendees, were cancelled.
The agency had scheduled the courses to teach 766 local authority representatives how the new performance management regulations worked.
Those council staff would, in turn, have trained local schools.
But the agency was working from the draft regulations. Deal-making and union legal action delayed the final publication until this week.
John Dunford, general secretary of the ASCL union which helped draft the new regulations, said it had become apparent on the morning of the first workshops that the TDA presentations were not in line with the new regulations.
"We were facing a situation where a confused message would have gone out to schools," he said.
Ian Draper, an education training consultant who had travelled down from Nottingham for the Heathrow course, said he had not been surprised at the cancellation: "Difficulties seemed inevitable when you are dealing with a number of different groups with different vested interests at stake."
The final cost to the taxpayer of the 16 cancelled courses has not yet been tallied, but may run into tens of thousands of pounds. The cost of the Sheraton Heathrow course cancellation alone is estimated at more than pound;6,000.
Local authorities have been invited to send their itemised expenses to the TDA.
Pat Collarbone, the executive director of TDA Development, acknowledged the disruption caused to local authority representatives but said they were being booked on to new courses.