Peter Ireland, appointed last term to succeed Valerie Bragg as head of Kingshurst City Technology College, left Nelson Thomlinson school in Wigton in the summer.
In his 12 years as head there, progress in GCSE results had made it one of the 30 most improved schools in the country with 72 per cent of pupils last year gaining five or more top grade passes, compared to a national average of 47.4 per cent.
Mr Ireland told parents when he left that he "truly believe(d) Nelson Thomlinson to be the best comprehensive school of them all".
Now he wants to go back to it. But he will have to wait until the New Year before he discovers if he can have his old job back.
The Nelson Thomlinson governors included Mr Ireland on the shortlist of candidates for the headship and interviews were due to take place last week.
But Cumbria County Council stepped in to advise them that they should start the whole process again. A fresh selection panel will consider applications and conduct interviews after Christmas. William Thallon, 39, who was Mr Ireland's deputy for his last two years and is not applying for the headship, has stepped in as acting head until Easter.
At Kingshurst, meanwhile, assistant principal Ann Jones has been appointed as acting head for a year while the governors look for a new permanent head.
The reason for Mr Ireland's sudden departure from Kingshurst is shrouded in mystery and he could not be reached this week. Under Valerie Bragg's leadership, the college has established a very strong inclusive identity, with an extended day and a flat staffing structure.
All pupils aged 14 to 16 take vocational courses as well as GCSEs and most take a vocational qualification in the sixth form too. It is one of three schools in a federation run by 3Es, the commercial arm of Kingshurst of which Valerie Bragg is now chief executive.
The recent inspection report on Nelson Thomlinson, a mixed comprehensive with 1,150 pupils, singled out for praise Mr Ireland's "very strong leadership" and "unswerving vision for the school's continued progress in achieving ever-better examination results".
But it said the school should do more for low achievers and that the governors should play a more active and critical role. And it criticised the school's very high number of fixed-term exclusions, putting it well into the top third nationally for schools of its size.