The IHS Markit/CIPS Purchasing Managers' Index rose to 55.6 in November from 53.7 in October, its highest since December 2017 and above an earlier flash reading of 55.2, bucking a gloomier picture from other sectors hit harder by COVID.

"The upcoming end to the Brexit transition period ... led to rising levels of input purchasing, stockpiling of raw materials and stronger gains in new export business as EU-based clients brought forward orders," data company IHS Markit said.

Britain and the EU have so far failed to agree a deal to allow tariff-free trade from Jan. 1, and even with a deal many exporters fear lengthy delays at ports due to new customs requirements.

"Whether the upturn of manufacturing production can be sustained into the new year is therefore highly uncertain, especially once the temporary boosts from Brexit purchasing and stockbuilding wane," IHS Markit director Rob Dobson said.

November saw the biggest rise in purchases of raw materials since March 2019, the biggest rise in export orders since January 2018, and the sharpest boost to optimism since 2014.

Factory output, which is only one component of the total PMI, also accelerated. But it showed slower growth than over the summer as the second wave of COVID cases reduced demand for some consumer goods, where new orders fell by the most in six months.

The most recent official data showed that factory output in September was almost 8% lower than a year earlier, similar to the rest of the economy.

Manufacturing is also still experiencing job losses, with the PMI showing that factories cut staff numbers for a tenth consecutive month, the longest decline since the 2008-09 recession after the global financial crisis.

(Reporting by David Milliken; Editing by Catherine Evans)

By David Milliken