Oxford has become a boom city, with about 400m of investment in the last five years, a report reveals today.

But it is in danger of becoming a victim of its own success, as the city will have to work harder than ever to retain its stature as a working mix of the historic and very modern, the reportit warns.

The glossy 41-page review document produced by Oxford City Centre Management an office funded jointly by public and private sectors was today being sent to 280 businesses.

City centre manager Marcus Lapthorn, the co-author of the report, details how multi-million pound inward investment into shops, restaurants, pubs and public transport is continuing.

Oxford's economy appears to be doing well despite development sites in the city being limited by the listed-building status of many structures.

Mr Lapthorn said: "The review reflects a city that is increasing in vitality and is economically buoyant. "Looking forward, there is good cause for optimism. Projected levels of inward investment into the city for this year stand at a figure well in excess of 226m."

The city currently boasts one of the lowest amounts of retail space available for leasing in the UK. Just 0.84 per cent of the total is free.

But the report warns: "While Oxford still has a high level of rentals achieved, the lack of significant new retail space in the city centre, as compared to other comparable towns, may be a warning that other towns are threatening to overtake Oxford as a first-choice destination for regional shoppers."

The Oxford Transport Strategy is praised for raising bus use by eight per cent.

The report concludes: "This is a period of great change and great excitement for Oxford. There are significant challenges to be met, not least by those posed by competing towns within the region, but Oxford's competitive advantage lies in its history, its beauty and the determination to succeed of those who work within the city."