The Confederation of British Industry (CBI) downgraded its U.K. gross domestic product (GDP) growth estimates on Monday. The U.K. economy is expected to expand at 2.4% in 2015 and at 2.5% in 2016, down from its February estimate of 2.7% and 2.6% respectively.

"The recovery has built up a good head of steam and we expect to see solid, steady and sustainable growth carrying through into next year. Risks remain in the form of economic instability in Greece and a sluggish Eurozone, and clearly the EU referendum is a hot topic in Britain's boardrooms. Businesses now have certainty that the referendum is happening, but not the outcome," the CBI Director-General John Cridland said.