In this London mansion flat Arts & Crafts architecture meets 1970s luxe

There comes a moment in a young couple's life when the exhausted neutrals in their post-university flat begin to pall. As responsibilities grow and priorities change, they soon realise that shopping for lampshades is, in fact, fun and at this point house hunting tends to follow suit.

For the twentysomething owners of this London flat, that moment was the catalyst for the purchase of a grown-up space to match their maturing interests. When they bought it, however, it required more than a trip to Ikea to transform it into the home of their dreams. 'The flat needed complete renovation and detailed consent to meet the heritage planning requirements,' says Graham Green, one half of the design duo Keech Green, whom the couple called upon to aid them in these taxing tasks.

Part of a house that was built in 1848, it later became the home of a distinguished Edwardian architect who occupied the house from 1890 to 1930. Behind many significant London landmarks, the architect's extensive public portfolio is noted for its imposing monumentality but, in his domestic life, he favoured something more intimate. This can certainly be seen in his redesign of this house, where he worked in the Arts and Crafts style, introducing hand-crafted wood, delicately tinted stained glass and gentle references to the natural world.

In his day, the house sat in a fashionable corner of the capital but, as the twentieth century wore on, both the location and the house sank into decline. The area soon recovered, but the flat remained forlorn, and Keech Green's brief was to reinvent it as a relaxed, contemporary home, while paying due deference to its notable past.

Michael Keech and Graham Green have a considerable pedigree working with historic buildings, and were unfazed by the need to reinstate damaged cornices and missing marquetry. 'The most demanding aspect was to find suitable replacements for the Arts and Crafts chimneypieces and fire surrounds, some of which had been stolen and replaced with inappropriate later examples,' says Graham, who worked with Jamb to create appropriate reproduction period designs.

The original design for one of the floors centred on a handsome panelled hallway, where a coved plasterwork ceiling is whimsically adorned with a spider embedded in a dainty floral web. 'All the principal rooms flow out from here but, when we began, the doorways were of different heights,' says Graham. 'Our first decision was to rationalise it.'

To unite the space, they evened out the door frames and added matching panelling to some adjoining rooms. They also opened up the division between the spacious drawing room and what had once been a library to create a dining area.

Though the couple had a fine taste for antique furniture, the intention was never going to be period pastiche. There was, on the other hand, initially some discussion about exactly what form of 'modern' the owners were looking for.

'When we first started talking, they showed us a red Perspex chair,' says Graham. 'We realised fairly quickly, however, that they didn't want a New York warehouse.' It would have been surprising if they had, since Keech Green are designers known for interiors that are soothingly classic. Graham trained as an architect, Michael as a retail and theatrical designer, and the two met when working for Ralph Lauren. There they helped develop the signature country-house look - a style they later successfully applied to a myriad of international projects from Scottish castles to Italian villas.

Here, the owners were seeking something more urban, if equally timeless, but they also had a number of specific requirements. These included: easy-to-use entertaining space for large and small parties; a designated room to cheer on their favourite football team, Chelsea; and high-style housing for their collection of tropical fauna.