LONDON - British factories reported the biggest fall in orders this month since late 2016 after a recent push to build up stocks of goods in advance of a Brexit that never came, a survey showed on Tuesday.

The Confederation of British Industry's (CBI) monthly order book balance fell to -10 from -5 in April, its lowest level since October 2016 and below all forecasts in a Reuters poll of economists.

The fall represents a disappointing reading as the CBI's order gauge, which is not seasonally adjusted, usually rises in May.

Overall, the survey suggested the boost to manufacturing from the rush to stockpile ahead of the original March 2019 deadline is subsiding quickly, with factories now lumbered with the greatest stocks of finished goods since 2009.

Export orders fell at the fastest rate since July 2016, the CBI said.

"These results provide further evidence that manufacturers have been stockpiling at a rapid pace as part of their Brexit contingency plans," CBI economist Anna Leach said.

"When combined with a sharp decline in order books, it's clear why manufacturing firms are so keen to see a swift end to the current Brexit impasse." (Reporting by Andy Bruce, editing by David Milliken) ((+44 20 7542 7748; uk.economics@reuters.com))