The London market was lower in afternoon trading as traders digested official data showing that the cost of living rose last month following the country's Brexit vote.
The FTSE 100 Index fell 25.5 points to 6915.7 after the Office for National Statistics said consumer price index inflation rose to 0.6% from 0.5% in June, its highest level since November 2014. Economists had expected inflation to remain unchanged in July from June.
The FTSE 250 Index lifted 69.3 points to 17998.6.
IG market analyst Joshua Mahony said: "The figure was slightly more than economists had expected, but it doesn't yet move the dial for the Bank of England's monetary policy makers, who have arguably shifted their focus to growth and jobs in the wake of the referendum result."
Mining giant BHP Billiton reported a record $6.4bn (£4.9bn) loss, as slumping commodity prices, a bad bet on shale gas and the costs related to the Samarco dam disaster in Brazil continued to take their toll on the company.
But the group added it expects free cash flow to double to more than $7bn in the current year after commodity prices have stabilised. This sent top flight mining shares higher across the board, with BHP lifting 34.5p to 1077p.
In afternoon trading the biggest risers on the FTSE 100 Index were Antofagasta (+37p to 551p), BHP Billiton (+34.5p to 1077p), Anglo American (+28.5p to 901.2p), Glencore (+4.9p to 197.9p) and Rio Tinto (+56p to 2491.5p).
The biggest risers on the FTSE 250 Index were EasyJet (-25p to 1062p), International Airlines Group (-7.5p to 395.3p), St James's Place (-16.5p to 963p), Shire (-80p to 5075p) and Relx (-21p to 1450p).
In afternoon trading the biggest risers on the FTSE 250 Index were Hochschild Mining (+28p to 322p), Amec Foster Wheeler (+36.5p to 554p), PayPoint (+60.5p to 1045p), Countrywide (+11.9p to 250.6p) and Morgan Advanced Materials (+12.7p to 298.7p).
The biggest fallers on the FTSE 250 Index were BGEO Group (-86p to 2875p), Sophos Group (-6.9p to 241p), JRP Group (-2.2p to 91.8p), William Hill (-5.8p to 306.7p) and G4S (-4.1p to 223.2p).