Leading a school in London is a bit like being in charge of repainting the Forth Bridge - a "relentless endeavour in which nothing ever appears to be fully sorted", according to a new study.
Whether it is meeting the needs of an ever-changing student population or dealing with the fallout from gang culture, crime and family breakdown, the pressures on school leaders in the capital are incessant. Yet almost all those who took part in the study had something positive to say about their jobs.
"It is addictive in a way," said one. "Colleagues and friends who go to teach outside the area may have an easier life but they miss the energy levels and diversity."
The top concerns of the 82 headteachers and deputy heads interviewed for the research were staffing, pay and retention.
"We can get young teachers who want to live and work in London because it's a fun place to be, and we can get people for senior management positions because if people have decided to stay in London then they are going to go for promotion," said Alasdair Macdonald, head of Morpeth secondary school in Tower Hamlets, east London.
"But frequently it's middle management where the problem arises because people think that they should move out of London to have a family."
Other heads reported that teachers were demanding extra money to stay in post. A head of music, for example, had two management points after just one year's teaching. But all those surveyed said their schools had been badly hit by last year's funding crisis. There was a strong feeling that London schools were simply not funded to meet the needs of their communities.
The transient populations of many of these communities mean high pupil turnover. A deputy head from Greenwich said: "There is a constant sense of loss when we put a great deal of energy and effort into children who arrive, and then they leave before we can see any of the results of our investment."
Schools with their own strong culture could demonstrate the value of diversity to visitors, parents and pupils.
However, diversity brings challenges. Several school leaders reported an increase in Islamophobia, while one remarked that children from war-torn countries often bring their anger and violence with them. "People who cannot articulate their needs because of language problems can become angry and aggressive," said another.
In general, ethnic-minority students were doing well because of their parents' high expectations. But some heads and deputies were concerned about a "white underclass" of pupils with a dismissive attitude towards learning. As one contributor put it: "We have a low number of parents with any experience of further or higher education. Some of them are anti-education. As girls grow older their attendance goes down, mainly because of childcare duties."
It is the sheer scale of these problems that makes London different, according to John West-Burnham, senior research adviser at the National College for School Leadership and one of the authors of the report.
"All the problems in London are found in other urban areas, but in London they come together in extreme numbers," he said.
In their report, Professor West-Burnham and co-author Professor Kathryn Riley point to the extremes of poverty and wealth in the capital, and the fact that around 42 per cent of pupils in inner London speak English as an additional language, compared to an average of 8 per cent for England as a whole. Contributors thought it was crucial for school leaders to understand other cultures.
"Many pupils are victims of war. Racism and the range of religious issues impacts directly on my work," said one headteacher.
With much of their time taken up with supporting children and their families, heads also needed to be highly committed to their communities.
Resilience was another important quality for London heads, with many paying a high price for the long hours they worked.
"They talked about relationship breakdown and families suffering, but at the end of it all they still had a mission," said Lynn Gadd, head of Copthall secondary school in Mill Hill. Together with Hasan Chaudhry, a primary head, she carried out the interviews for the study.
Interviewees mentioned the value of collaboration, especially through cross-phase networks. In Tower Hamlets, for example, heads were part of a mini-education action zone. But London-wide networks were thin on the ground.
"Much lamented was the demise of the Inner London Education Authority programme, which brought together new headteachers across London to meet other leaders, discuss what they were doing, and to lay the foundations for professional relationships which had been sustained over many years," says the report.
Interviewees and other leaders will be invited to a conference in April to discuss the study, commissioned by the NCSL for the London Leadership Strategy, part of the London Challenge headed by Tim Brighouse, the capital's schools commissioner.
Alan Davison, operational director of the strategy, said: "We are working with the Institute of Education to modify our programmes so that we can make sure leadership development reflects the needs of colleagues."
Educational Leadership in London by Professors Kathryn Riley and John West-Burnham is available on the NCSL's Talk2Learn website
The report recommends:
* Access to advice on cultural and ethnic issues
* Opportunities for school leaders to "recharge their batteries", for example through sabbaticals and retreats
* Skills-based training in areas such as conflict management and working with diverse communities
* Support for the personal well-being of school leaders
* Links with schools in the UK and other countries
* Programmes to help school leaders get the most out of staff