Growth in the service sector businesses that drive the UK economy slowed to its weakest rate in four years last month, according to a survey that gives the Bank of England enough evidence to justify cutting interest rates in this week’s finely-balanced decision.

The Chartered Institute of Purchasing and Supply and the research group NTC said on Wednesday their closely watched index of services activity fell from 53.1 in October to 51.9 in November, weaker than the modest slowdown expected and following a bigger drop the previous month. Confidence over future business dropped to its lowest level since March 2003.