Last week, before revealing to journalists the three rival schemes for rebuilding Pimlico School, deputy head Peter Jefferies had to escort two intruders off the premises. That's one of the problems with a school in central London with 14 entrances.
The day before, water had suddenly flooded through the roof of Mr Jefferies' office and he had had to move everything to one end. That's another problem with a flat-roofed, glass-and-concrete structure with internal gutters.
These and other difficulties explain why this flagship comprehensive, renowned for music, art - and its glass and concrete building - is to be rebuilt on the same site at a cost of some Pounds 18.5m. For the 25-year-old building, striking as it is, is a nightmare to work in. Corridors are too narrow, useful space in classrooms too small, windows open only six inches and in the summer this enormous building behaves exactly like the greenhouse it is. The council says it costs Pounds 370,000 a year to maintain.
After Westminster's bid for conventional funding to rebuild the school had produced a capital allocation of only Pounds 2.5m in 1995, the council decided to explore alternative sources of finance. The size of the school - 1,350 pupils - and its prime site made it an obvious candidate for the Private Finance Initiative.
The unusual layout of the four-and-a-half acre site means up to a quarter is wasted. The winning bidder would create a school and grounds of the same size as at present but keep the surplus acre for a lucrative housing scheme.
It would also provide non-teaching services such as security and cleaning in return for regular payments, and keep the proceeds of letting sports and other facilities out of school hours.