In February this year, the Government announced that capital investment in schools will reach pound;5.1 billion in 2005-6. The news must have come as music to headteachers’ ears. Under the Building Schools for the Future scheme, 10 local education authorities, including Sunderland and Waltham Forest, will be able to improve and renovate their existing school buildings and bring them into the 21st century.

The decades immediately after 1945 saw a similar flurry of renovations as classrooms and annexes were added. Interestingly, it is some of these very annexes which need to be renovated, rather than the original buildings which date back to Victorian times. Clearly, lessons need to be learnt before excitable heads start calling in contractors and architects.

At Hargrave Park school in Islington, north London, headteacher Wendy Meredith is putting away the displays for the 125th anniversary of the building. The 1870 Education Act created the Board schools - Victorian Gothic castles that still dominate their neighbourhoods and continue to make up a sizeable proportion of the country’s primary schools.

Across the City of London in nearby Tower Hamlets, acting head Jenny Payne wants the private finance initiative (PFI) to fix the leaking roof on the one-storey Olga primary school, built in 1982. Tiles are often dislodged over the weekend by children setting up makeshift camps on the roof of the low-slung building.

At the other end of the scale, the pound;12 million renovation of Kingsdale secondary school in Dulwich, south London, is raising expectations in many quarters. Designed by architects De Rijke, Marsh and Morgan, press interest in the project is fanning the high hopes that teachers, students and parents hold for the new-look school.

Hargrave Park is a model of the Victorian innovation in public education, one which many educators still look to. For many, the Board schools are iconic - the image of what schools should look like. This stereotype is propounded by literature and film, from Leo Baxendale’s Bash Street school in The Beano comic to the comprehensive depicted in the 1967 film To Sir, With Love.

The Board school buildings are loved for their character, preposterously high ceilings, nooks and crannies, and solid buildings. Hargrave Park’s alterations revealed brick walls three feet thick. Years ago, there was even a swimming pool on the ground floor.

The Board Schools were factories of learning with 50 pupils to a class.

Hargrave Park once housed three schools, each on top of the other, with parquet-floored assembly halls.

Demographic changes have made it impossible to sustain two-form entry, and it was threatened with closure until it rallied under its indefatigable head. The building is under-occupied, so Ms Meredith lets out space to Agenda 21, the United Nations Environment Programme, and other organisations.

Not all teachers are fans of the Victorian buildings. Kate Moorcock, a primary teacher in Tower Hamlets, jokes that the children were a lot smaller when the Board schools were built and were therefore not as cramped as they are today. Latest figures which put the borough’s rates of childhood obesity at a whopping 35 per cent support Ms Moorcock’s theory.

Pandora Kreizman, a teacher at Parliament Hill school in north-west London, contrasts the old school building favourably to the modern annexes, which she finds “baking hot in the summer because of all that glass”.

The ungainly hybrid of 1880s and 1960s is a consequence of the raising of the school-leaving age, which spawned many additional blocks in the decades after the Second World War.

But Kingsdale school was entirely rebuilt as new in the 1950s by what the cultural critic Lewis Mumford called the “colossal and competent” London County Council’s architect’s department, which also built the Royal Festival Hall on London’s South Bank.

In the 1970s, students called the public address system “Big Brother”, while early leavers were rumoured to have barricaded themselves in the head’s office to play reggae records over it on their last day.

Under today’s head, Steve Morrison, Kingsdale brought in a range of advisers such as the Architecture Foundation, School Works and the pointy-headed policy wonks at the think-tank Demos to transform the school with a dramatic programme of works. The site architect, Philip Marsh of De Rijke, Marsh and Morgan, is at pains to involve the school’s management, staff and students in the process.

The LCC architects built a Lego-like box on columns whose four sides surrounded an open quad with a central entrance under the overhanging second and third floors. Corridors run all around, with spacious glass-encased concrete stairwells. On top of the LCC’s technical drawing perpendiculars and horizontals, Mr Marsh and builders Galliford Try have dropped the shaped curves of computer-aided design.

The quad is now covered with an adjustable light-filtering roof, and the wooden frame of a great geodesic pod-shaped auditorium and library have spawned in the oblong space. Mr Marsh knows the 1950s modernist design gives him a great canvas to work on - even if a lot of the innovations, such as irreparable honeycomb plaster walls, were concerned with scrimping on materials.

One of the disappointments with the two new tranches of cash for rebuilding schools under the 1998 and 2002 spending reviews is that they have encouraged renovation instead of new buildings designed and built from scratch.

School architecture has been influenced by the brownfield development preference of Lord Richard Rogers’s Urban Task Force. That suggests more architectural doodling on top of old buildings, as is the case with Kingsdale. Computer-aided design leads to a lot of curves and pods. The revolution in building materials will see a lot more wooden frames and maybe straw walls, too.

For Mr Morrison and his deputy, Catherine Bryan, the rebuilding of Kingsdale is a narrative of redemption from failure that engages the whole school in its collective effort. Building work could be a distraction, but it is being used to convey promise by the teaching staff and builders.

For Jenny Payne at Olga primary, rebuilding under a stalled PFI scheme is more prosaic. Her low brick building spreads out in front of the old Board school - now converted into flats - and won awards in 1982. But the open-plan design, which was inspired by the informal teaching theory of the time, left Years 3, 4, 5 and 6 sharing one partitioned space.

For peace and quiet, teachers have built divides. Now, the renovation means a chance to put walls in to make closed rooms, but these are cramped.

Unlike Mr Morrison’s happy situation at Kingsdale, her builders do not consult. Maybe Ms Payne will be cheered by Hargrave’s 125 years, or Kingsdale’s renovation experiences. Meanwhile, a roof that doesn’t leak would help.

WHICH TYPE IS BEST TO TEACH IN?

Victorian Board Schools

Advantages: Full of character. High ceilings that give classrooms a light and airy feel. Thick walls for better soundproofing. Toasty radiators run from a sturdy boiler.

Negatives: Hard floors that raise noise levels. Victorian children were smaller so rooms not too spacious. Gloomy - if not downright spooky.

Stairwells and corridors are often too narrow.

1960s comprehensive

Advantages: Modernism is cool again. Light and airy rooms and corridors.

Covered walkways mean pupils and staff can stay dry when they move between buildings.

Negatives: Glass expanses create a greenhouse effect in summer; materials such as veneer and hardboard come away from the walls and polystyrene tiles can be dislodged from false ceilings. Pink Floyd-style classroom alienation. Flat roofs have a tendency to be leaky.

1980s open-plan

Advantages: Fewer storeys mean fewer stairs to climb. Buildings are harder to get lost in. Materials are usually of a higher quality than the 1960s comprehensive - or at least haven’t collapsed yet.

Negatives: ‘Informal teaching’ just means you cannot hear yourself think.

Architects tend to stint on space. You can spend a lot of energy adapting the building to meet realistic needs.