The terrorist attacks in Paris have had an affect on the French economy, according to a closely watched survey.
The purchasing managers' index (PMI) survey by Markit found that the French services sector scored 51.3 in November, down from 52.7 in October. Any figures about 50 indicates growth.
Although the survey does cover the period before the attacks took place on 13 November, Markit said that around 60% of responses were received after the attacks.
Mr Williamson said: "Clearly there's been a cut in footfall and any sort of feel-good factor amongst consumers in the wake of the horrific events.
"But history does tell us that these events tend to have a very short-lived impact."
Elsewhere, Markit's "flash" manufacturing PMI grew to its highest level in 19 months. It said that rest of its data suggested "a more encouraging picture of France continuing to lift itself out of its gloom".