Blue chip shares made modest gains, shrugging off disappointing construction data, which suggests the British economy is slowing down.
A slowdown in housebuilding eased UK construction in March, as the closely-watched Markit/CIPS Construction Purchasing Managers' Index (PMI) fell to 52.2 from 52.5 in February. Economists had expected the figure to remain unchanged.
The FTSE 100 Index lifted 33.6 points to 7316.3 in afternoon trading, with the construction survey coming a day after weaker-than-expected manufacturing PMI data.
Spreadex financial analyst Connor Campbell said: "That's another piece of evidence to suggest that the UK economy is beginning to falter after the solidity of the fourth quarter of 2016 and first quarter 2017, with the country's ever increasing inflation one of the major issues."
In a light day for corporate news supermarket Sainsbury's was among the biggest fallers in the top flight after losing market share in a poll by the respected retail research group Kantar Worldpanel.
The country's second largest grocer saw its market share fall 0.7% to 16.4% in the 12 weeks to 26 March compared to the same period a year ago, the data said. Shares fell 6p to 257.3p.
The biggest afternoon risers in the FTSE 100 Index were Fresnillo (+43p to 1595p), Randgold Resources (+150p to 7185p), WPP (+36p to 1768p), Rio Tinto (+65.5p to 3252p) and BHP Billiton (+23p to 1251p).
The biggest afternoon fallers in the FTSE 100 Index were Mediclinic International (-18p to 692.5p), Sainsbury's (-6p to 257.3p), Associated British Foods (-47p to 2554p), Morrison (Wm) Supermarkets (-4.2p to 233.5p) and Royal Bank of Scotland Group (-3.2p to 236.7p).
The biggest afternoon risers in the FTSE 250 Index were Sophos Group (+32.7p to 304.8p), Rotork (+10p to 256.1p), Berendsen (+27.5p to 768.5p), BGEO Group (+100p to 3333p) and Evraz (+6.8p to 231p).
The biggest afternoon fallers in the FTSE 250 Index were Allied Minds (-15p to 255.4p), Henderson Group (-5.4p to 230.6p), Carillion (-4.8p to 220p), Travis Perkins (-30p to 1470p) and Millennium & Copthorne Hotels (-8.8p to 441.5p).