U.K. services PMI slipped to 60.3 in September (flash 60) from 60.5 in August.
The sharp gain in activity rounds off the best quarter since Q2 1997.
The surveys suggest the economy expanded by up to 1.2% in Q3, the "fastest growth rate since the pre-crisis days of 2007," says Markit.
"Growth is clearly running much faster than the government and Bank of England anticipated earlier in the year. If such strong expansion persists, it's hard to see how the Bank can avoid a review of its forward-guidance policy," Markit adds.
GBP-USD flat at $1.622, FTSE 100 +0.2%. (PR)