Blue chip shares struggled for direction as hotels and coffee chain giant Whitbread dragged on the market.
The Premier Inn and Costa owner saw tougher competition eat into trading at its two key chains, missing forecasts and sending its shares sharply lower.
The FTSE 100 Index edged 15.3 points higher to 7280 in afternoon trading, in a session that also presented traders with mixed economic data.
Whitbread said its two divisions drove group underlying profit before tax up 6.2% to £565.2m ($732.7m), against a prior 52-week comparative to 2 March. But this fell short of City estimates of £557m.
The firm said that although the first seven weeks of its new year had started well, it added "we remain cautious and expect a tougher consumer environment than last year". Shares tumbled almost 8%, or 332p to 3975p.
IG chief market analyst Chris Beauchamp said: "Brexit worries have hit Whitbread, with the firm deliberately keeping a cautious outlook for the coming year despite a good start for its Costa coffee and Premier Inn brands."
In economic news, the UK government's deficit fell to its lowest level since the start of the financial crisis in the last financial year, but was still slightly higher than official forecasts, according to the Office for National Statistics.
Public sector net borrowing excluding taxpayer-backed banks, decreased by £20bn in the year to March 2017 to a total of £52bn. The Office for Budget Responsibility had predicted a full-year reduction of £20.3bn only last month, but the target was missed as borrowing jumped at the end of the period.
The biggest afternoon risers in the FTSE 100 Index were Hikma Pharmaceuticals (+39p to 1881p), Ashtead Group (+32p t0 1657p), Royal Bank of Scotland (+4p to 253.2p), Hammerson (+9p to 604p) and Shire (+67.5p to 4631.5p).
The biggest afternoon fallers in the FTSE 100 Index were Whitbread (-332p to 3975p), Kingfisher (-5.5p to 331.7p), Associated British Foods (-45p to 2834p), Randgold Resources (-105p to 6865p) and Anglo American (-16p to 1113p).
The biggest afternoon risers in the FTSE 250 Index were Elementis (+15.3p to 313.7p), Ascential (+15p to 345.8p), Weir Group (+77p to 2080p), Carillion (+6.7p to 223p), Allied Minds (+4.1p to 165.7p).
The biggest afternoon fallers in the FTSE 250 Index were Cobham (-3.6p to 131.7p), Dunelm Group (-16p to 608p), Vectura Group (-3.3p to 139.3p), Millennium & Copthorne Hotels (-9.2p to 447.7p) and Wizz Air Holdings (-28p to 1770p).