The blue-chip FTSE 100 ended down -0.1%, with pharmaceutical and construction stocks leading declines, while most mining stocks were top boosts to the index.
Miners Rio Tinto, BHP Group and Glencore were among the top gainers on the index.
The mid-cap FTSE 250 index was flat.
"With the general outlook being still largely positive on UK equities, markets have taken a little breather after consistent gains over the past few sessions," said Michael Baker, an analyst at ETX Capital.
The FTSE 100 has recovered nearly 35% from its March 2020 lows and is now 12% below its peak last year, led by stimulus support, but a surge in infections and lockdowns have recently slowed the pace of gains.
Prime Minister Boris Johnson said on Monday he would plot a cautious but irreversible path out of the COVID-19 lockdown this week after the vaccination of 15 million vulnerable people.
Glencore jumped 2.0% as it reinstated its dividend after its net debt fell by 10% in 2020, helped by surging commodity prices in the second half.
BHP Group rose 1.5% after the miner reported its best first-half profit in seven years and declared a record interim dividend.
British outsourcer Serco climbed 4.8% and was the second best performer in the midcap index after saying it would buy consulting services provider Whitney, Bradley & Brown Inc from an affiliate of H.I.G. Capital for $295 million to bolster its North American defence business.
Miner Petra Diamonds gained 6.1% as its half-year core earnings jumped 20%, although it cautioned that the pandemic might impact its ability to operate within its covenants.
(Reporting by Shivani Kumaresan and Amal S in Bengaluru; Editing by Vinay Dwivedi and Jonathan Oatis)
By Shivani Kumaresan, Amal S and Shashank Nayar