Blue chip shares fell as traders weigh up US President Donald Trump's protectionist inauguration speech.
America's 45th President said his administration "will follow two simple rules – buy American and hire American". Trump has previously threatened to impose tariffs as high as 45% on Chinese imports.
The FTSE 100 Index fell 35.7 points to 7162.7, as top flight shares fell 0.08% below where they started the year in early trading. The FTSE 250 fell 53.4 points to 18097.5.
The Footsie had started the year with a bang repeatedly setting new all-time highs on a record-breaking 14-day run of gains buoyed by Trump's earlier pledges to cut corporate taxes and spend $1trn ($818bn) rebuilding US infrastructure.
IG chief market analyst Chris Beauchamp said: "Markets are in retreat as the new week gets underway, with the Trump bounce slowly running out of steam."
The pound also hit a five-week high, up 1.04% to $1.2465 against the dollar.
Top flight shares are less appealing to investors when the pound rises because most of the sales of firms in the index are earned aboard, hitting revenues when translated back into sterling.
In London, Bookmaker Paddy Power Betfair was the biggest faller in the top flight after it said Donald Trump's unexpected US election victory and a raft of "customer friendly" football games cost it £40m ($50m) in the final quarter of the year.
The bookmaker, which agreed a merger in 2015, said Trump sweeping into the White House cost the group £5m.
Bookmaker Paddy Power Betfair said Donald Trump's unexpected US election victory and a raft of "customer friendly" football games cost it £40m ($50m) in the final quarter of the year. The bookmaker said Trump sweeping into the White House cost the group £5m.
It said favourites winning football matches in December also hit its bottom line. During this period Chelsea, Manchester United, Tottenham Hotspur, Liverpool, Manchester City and Celtic all enjoyed strong runs.
Shares in the bookie fell almost 4%, or 330p to 8345p.
The biggest risers in the FTSE 100 Index were Antofagasta (+34.5p to 796.5p), Fresnillo (+44p to 1446p), Anglo American (+29p to 1318.5p), Glencore (+5p to 323.3p) and Randgold Resources (+100p to 6815p).
The biggest fallers in the FTSE 100 Index were Paddy Power Betfair (-330p to 8345p), Royal Bank of Scotland (-4.5p to 216.4p), Sage Group (-11.5p to 632p), Barclays (-3.8p to 223.6p) and Sainsbury's (-3.8p to 259p).
The biggest risers in the FTSE 250 Index were Hochschild Mining (+15.4p to 241.2p), SSP Group (+18.8p to 409.8p), Ferrexpo (+5.4p to 135.5p), Bovis Homes (+28p to 825p) and Kaz Minerals (+11.5p to 421.8p).
The biggest fallers in the FTSE 250 Index were Inmarsat (-23.5p to 632.5p), Hunting (-20.5p to 597p), Aldermore Group (-7.1p to 208.7p), Greencore (-7.3p to 228.7p) and Virgin Money (-8.5p to 296.5p).