One of London's most delightful minor landmarks is to be rescued from years of dereliction. Boone's Chapel, built to serve a row of almshouses in 1682, has stood forlornly on Lee High Road, the modern A20, and was last used in 1945 for a celebration VE Day service. The handsome almshouses on either side were demolished in 1877.

Charles MacKeith, the architect entrusted with repairs, says, “We couldn't understand why the chapel hadn't vanished at the same time as the almshouses until late in 2006 we discovered the burial vault of the founder, Sir Christopher Boone, beneath the chapel”. Work has been delayed for a year as a result. Boone's coffin had largely disintegrated, but that of his wife Mary, who survived him by 35 years, dying in 1721, survived in remarkably good condition. Now the vault has been resealed and restoration began last week.

The chapel, which had been used as a reading room until the Second World War will become a design office for MacKeith and his partner, Madeleine Adams. A condition of the grant from the Heritage Lottery Fund is that it will be open 30 days a year. MacKeith explains: “We will open it at weekends, holding exhibitions of local interest. Exhibits can be laid out on the large central drawing table and all our files will be out of sight.”

Though long attributed to Sir Christopher Wren, and very much in his style of warm, red brick with emphatic stone trim, the chapel is now thought to be the work of his associate Robert Hooke.

Graffiti have been removed, and one might imagine the next step would be to clean the red brick. However, expert examination has shown that the present dark hue is not simply the result of pollution. In the late 19th century the bricks were tinted with a soot wash and repointed with black “penny struck” pointing (with a fine line in the mortar about the width of a penny). “We will be carrying out only the lightest brush cleaning,” says MacKeith.

Internally some fine, apparently original, plasterwork remains around the window behind the altar. The restoration is being carried out by the Blackheath Historic Buildings Trust, after years of agitation by the Blackheath Society. When the £500,000 restoration is complete in a year, its work may be far from over as it now appears that the Regency Merchant Taylors' Almshouses behind the chapel do not meet the latest regulations.