U.K. services PMI dropped to 60 in November from 62.5 in October and missed expectations of 62.
Activity and new business continued to rise at "historically sharp rates," says Markit.
Service providers added extra staff, while backlogs rose steadily.
The PMI surveys for services, manufacturing and construction indicate that GDP is on track to grow more than 1% in Q4.
However, one note of caution is that inflation reached the highest rate since May 2011 as service providers reacted to increasing costs.
The FTSE 100 is +0.1% and the pound is -0.25% at $1.635. (PR)