Mr Emms, 47, had been invited to give a lecture on how to survive in the wild to pupils at Allhallows School, which is perched on remote clifftops near Seaton, south Devon.
The talk had the stirring title of 'Ripping Yarns', evoking images of appalling hardships and stiff upper lips in the days of the British Empire. Things began to go wrong quickly.
He decided to go for a stroll before delivering his talk to the 260 pupils at the pounds 3,100-a-term school. When he had failed to return after an hour staff at Allhallows began to fear for his safety.
Allhallows is the only school in Britain to have its own Auxiliary Coastguard Unit. This set off in search of Mr Emms, a lecturer from Dittisham, near Dartmouth, Devon.
When it failed to find him, the police and two other auxiliary coastguard units were called in. By this stage 40 local people, five police officers, a tracker dog and two helicopters were involved.
Jeremy Willis, the school's head of music, said yesterday: 'One team scaled the cliff face, cutting through bushes and eventually found him, after hearing cries for help. He had gone for a walk down the cliffs and got himself into trouble in an area where it is virtually impossible to be found.'
The search, which ended early yesterday, took five hours, and Mr Emms had strained the rescuers' patience near to breaking point. Despite having only a groundsheet and no food he said that he wanted to stay on the cliff ledge.
A police spokesman said: 'He just wanted to stay there and come down when he was ready. Eventually he was talked into getting winched into the helicopter.'
The lecture was never delivered and the school has decided not to invite him back. Mr Emms was not available for comment yesterday.