The export-oriented FTSE 100 fell 0.3% by 0829 GMT, while the domestically-oriented FTSE 250 also shed 0.3%.
Global markets were subdued as investors braced for U.S. inflation data due this week and eyed results of midterm polls that could signify a power shift in Washington. [MKTS/GLOB]
In the UK, travel and leisure stocks led declines after pub group J D Wetherspoon slipped 3.7% after warning that its sales had slowed in October.
Marks & Spencer dropped 1.2% as it warned of a "gathering storm" of higher costs and pressure on household budgets, and reiterated full-year profits would fall. The broader retail index slipped 0.5%.
Broadcaster ITV fell 4.4% as it forecast slightly lower ad revenue for 2022 despite a FIFA World Cup boost in the key Christmas quarter, and flagged a high degree of economic uncertainty.
(Reporting by Johann M Cherian in Bengaluru; editing by Uttaresh.V)