Britain's FTSE kept steady by rise in Vodafone

* FTSE flat, up around 7 pct since start of 2015

* Liberty Global (NasdaqGS: LBTYA - news) comments boost Vodafone

* Burberry falls after cutting 2016 guidance

* M&S shares rise after results

By Sudip Kar-Gupta

LONDON, May 20 (Reuters) - Britain's top share index held firm on Wednesday, as bid speculation lifted mobile network operator Vodafone, whose gains offset a slump in the shares of luxury goods group Burberry.

The blue-chip FTSE 100 index, which hit a record high of 7,122.74 points in April, was flat at 6,996.36 points going into the middle of the trading session. The index is up by around 7 percent since the start of 2015.

Shares (Frankfurt: DI6.F - news) in Vodafone, which fell 3.2 percent on Tuesday, advanced around 4 percent on Wednesday after the chairman of Liberty Global, John Malone, said the two companies would make a "great fit", reigniting long-running merger speculation.

Vodafone's rise offset the negative impact on the FTSE from a 5.5 percent decline at Burberry, after Burberry cut its 2016 profit guidance.

Retailer Marks & Spencer also progressed 1.4 percent after it reported a rise in annual profit for the first time in four years and unveiled plans to return excess cash to shareholders.

"Vodafone has helped the index a little bit. The FTSE looks fairly well anchored at the moment, with a slight positive skew," said Hantec Markets' analyst Richard Perry.

Admiral Markets' Darren Sinden said the FTSE looked well set for the rest of the year, provided that any market pullbacks did not push it too far below the 7,000 point level.

"I would be cautiously buying any dips below 7,000," he said.

(additional reporting by Alistair Smout; editing by Ralph Boulton)