Microsoft is running an unusual promotion for Office 2007, offering Londoners a free ride in any taxi with the application's logo.

The company has around 20 London taxis branded with Office 2007 livery which can be used by anyone between 7.30am and 9.30am for free.

The taxi rides must be confined to Zones One and Two and riders will get a postcard offering a free trial of the software.

"As the weather gets hotter and the tube more unbearable, we are helping London's workers have a better day by laying on free cabs to keep them fresh in body and mind," said Darren Strange, UK product manager for Microsoft Office 2007.

"Office 2007 is all about helping workers do their job better and, by allowing them to get a free taxi to work, we hope this will help them too."

The taxis will be in circulation until 8 May.