Let me remind you of Sheppard Robson. They were a personality practice of the 1950s and 1960s that - once the founders had retired - became a very dull commercial practice of the 1980s, but started to re-energise themselves in the late 1990s and are now once more a force to be reckoned with. Despite now being one of the largest firms in the UK. First-generation Sheppard Robson, let's not forget, won the 1960 competition for Churchill College, Cambridge, with a design heavily influenced by Le Corbusier's Maisons Jaoul in Paris. It's somewhat ponderous and conservative compared to Arne Jacobsen's very different St. Catherine's College, Oxford, of the same period, but undeniably good, and so the two colleges were listed simultaneously in 1993. Later, Sheppard Robson refined its university style in such early 1970s buildings as Collingwood College, Durham - a brick-clad, punched-window, spine-block aesthetic that proved durable and influential enough to be revived in the hands of younger university architects in the 1990s.

Then came the changing of the guard, the shift from public to commercial clients, and a great deal of mediocre large-floorplate office space around the City of London in the late 1980s boom. Luckily, the recession put a stop to that. Sheppard Robson shook itself out like every other practice. When recruitment began again, there was a pool of underemployed talent out there, some of it with impressive CVs. The practice decided that, this time round, it was going to look again for partners interested in design quality. And so Graham Anthony and Tim Evans came to represent the new face of Sheppard Robson.

Anthony - in a previous existence one of the superteam working on Richard Rogers' Lloyds of London building alongside people like Chris Wilkinson - was the man in charge of the rather good 1998 Motorola factory in Swindon, a showy piece of late high-tech. This and its calmer contemporary, Wilkinson Eyre's Dyson factory in Malmesbury, showed that there was architectural life in manufacturing industry yet. The slightly earlier office block known as the Helicon in the City had shown that something different was stirring within Sheppard Robson, but Motorola was the first project to break the lacklustre 1980s mould decisively. Toyota GB is meant to mark a further stage in the recovery plan.

Evans has a different pedigree. He worked closely with Terry Farrell through the 1980s before giving up on architecture for a while, exploring the world, then struggling to maintain his own practice, and finally, having been hit by a non-paying client, answering a Sheppard Robson ad for a short-term contract job. That was ten years ago. Three years ago, he became one of six new partners in one of the biggest reorganisations the practice had ever known. He and Anthony were specifically designated "design partners": they were to be the aesthetic stormtroopers. If Motorola was Anthony's first coup, then Toyota is Evans's.

There it stands, on a hillside outside Epsom, a great big £26million, 140,000 square foot office and marketing building hemmed in surprisingly closely by suburban villas. Were it not for the fact that its site was previously occupied by the motley buildings of a pharmaceutical company - so this counts as a "brownfield" development - this cheek-by-jowl proximity of big business and little houses might seem somewhat perverse.