16/10/2012 09:05 BST | Updated 15/12/2012 10:12 GMT

What Price on London's Heritage?

To the sound of ferocious opposition in the City Hall Chamber, last week London Mayor Boris Johnson approved the redevelopment of the historic Spitalfields Fruit and Wool Exchange.

The decision is a big loss to the local community and to this special part of the East End. But it's not just a loss to London socially and culturally, but also to its economy.

The case in favour was jobs and the Crossrail levy. But at what cost?

The Fruit and Wool Exchange opened in 1929 as a market for the fruit and vegetables coming off the ships flowing into London's Docklands. Its grand classical stone façade quickly established the building as a monument to London's preeminent role in global trade and its role as the epicentre of national distribution networks. It became a well-loved part of a thriving local community. Even when the market itself moved out in 1991, sixty small businesses of different sorts jumped at the chance to operate from the historic location. Many have traded from this building since.

The decision to redevelop threatens the intricacies of the area's social and economic fabric and will erode its character. It sets a dangerous precedent for the hallowing out of the neighbourhood, which is so steeped in history.

This is the sort of heritage we cannot afford to undervalue. It has enormous economic, social, and cultural value. One of London's major draws as a place to work, live and visit is the historic character of its neighbourhoods. One study of visitors to London found heritage was consistently cited as a highlight of their trip.

The Mayor's decision flies in the face of this.

Although the façade will not much change, it is more than just façades that matter. Areas can very quickly become stage sets. Historian Dan Cruickshank passionately argued against the proposal by describing the gorgeous white marble, carefully designed stairs, and other interior characteristics which will now be lost forever.

However, it is not just the decision itself that is wrong - it is the fact that the Mayor took over decision-making powers in the first place.

In this case, Johnson has not just ridden roughshod over local heritage. He has disregarded the wishes of local people and the local council. Tower Hamlets twice rejected this application before the Mayor took it upon himself to exercise rarely-used powers of 'call in' so that he could make the final decision.

In his fifth year as Mayor, this was only the fifth time he has wielded these powers. We have to ask just what made this case so special.

One possible answer is Crossrail. The Mayor's Crossrail levy means that every new development within areas which will be served by the new line must contribute to its costs. The contribution from the Fruit and Wool Exchange development is expected to be as much as £2,026,716.

The Mayor's planning unit's own report outlining the reasons for approving the Fruit and Wool Exchange project notes that funding for Crossrail was a consideration in the decision-making process.

So we know that the need to fund Crossrail was a factor in this decision. The question now is how much Crossrail tipped the balance.