The US economy kept up a strong rate of growth in the first half of the year, setting it on a course for its best performance in more than a decade.

Gross Domestic Product (GDP) expanded at an annualised rate of 4.2pc in the US, 0.1 percentage point faster than first estimated, marking the most rapid growth seen for four years, according to the US Bureau of Economic Analysis.

US GDP growth is reported on an annualised basis, rather than as an average of the last four quarters, as is the case in the UK and Canada. As a result, economists expect GDP to expand by close to 3pc this year, lower than the figure of 4.2pc may suggest.

However, this would still be the strongest growth since 2005 and well above last year’s GDP expansion of 2.2pc.