Shares have risen by more than 40 per cent in the past year and put on another two per cent after its latest trading update, as the FTSE 100 Index pulled out of its recent slump, adding 12.1 points to close at 6766.8.
A slight fall in oil prices on hopes that the Iraq conflict will not impact Middle East supplies helped steady nerves. However, investors were still cautious ahead of today's meeting of the US Federal Reserve when policymakers are likely to announce a further scaling back of quantitative easing.
Germany's Dax and France's Cac 40 gained while New York's Dow Jones Industrial Average was flat by the time of the close in London. The pound was firm on currency markets after figures showed inflation dropped to a four-and-a-half-year low of 1.5 per cent in May.
Sterling initially slipped against the greenback as the figure appeared to ease pressure on the Bank of England to raise interest rates but it closed only slightly lower at just under 1.70 and was a little ahead against the euro at 1.25
The inflation figure was offset by separate data showing house prices have been rising at their highest annual rate in nearly four years and Bank governor Mark Carney signalled last week that rates could rise sooner than expected.
Airlines recovered some of their poise, having recently been battered by a rise in oil prices on the back of the Iraq crisis.
British Airways owner International Airlines Group edged up 2.9p to 381.1p while low-cost carrier easyJet climbed 11p to 1446p, but travel operator Thomas Cook dropped 3.6p to 137.9p.
EasyJet's former boss Andy Harrison is now at the helm of Whitbread, where sales have continued to impress after better-than-expected like-for-like growth of 6.9 per cent in the first quarter of the financial year.
With no signs of a slowdown in growth at Premier Inn or Costa, the latest update prompted Investec Securities to remove its sell rating on the stock. Whitbread was 91p higher at 4259p.
Elsewhere in the top flight, shares in Shire rose by more than three per cent after Reuters reported that the pharmaceuticals company had hired additional advisers to handle potential takeover approaches.
Crest Nicholson delivered one of the biggest rises in the FTSE 250 Index after the housebuilder announced a better-than-expected rise in first-half earnings.
The biggest FTSE 100 risers were Shire up 124p at 3660p, Morrisons up 4.3p at 192.6p, Whitbread up 91p at 4259p and Tullow Oil up 15.5p at 872p. The biggest fallers were Ashtead down 55.5p at 831.5p, Kingfisher down 8.1p at 361.8p, Royal Mail down 10.3p at 478.4p and Friends Life down 6.5p at 315.3p.