Small businesses’ annual income is growing at its fastest rate since 2000, according to an annual index by Barclays Bank.

The Barclays Small Business Income Index shows that income levels climbed 20% in 2014 compared with the first quarter of 2000.

The research is based on an assessment of 600,000 customer accounts with businesses turning over less than £5 million.

Money flooding in to small firms recovered its pre-recession peak in 2013, but Barclays said the new figures represented a “step change in the strength of business activity”.

The latest figures reveal income climbing 8% in 2014 compared with 2013, the strongest rate of growth in 14.

Businesses in property management and maintenance saw the biggest increases, accounting for a third of growth in the sector overall.

Suppliers to the education and health sectors were also in rude health last year, occupying the fourth and fifth places in the top five income growers.

London continued to spearhead the charge, as businesses in the capital accounted for a quarter of all income growth this year.