Pru CEO departure pushes Britain's FTSE further from all-time highs

* FTSE 100 down 0.2 pct

* Thiam leaves insurer Pru (HKSE: 2378-OL.HK - news) for Credit Suisse (NYSE: CS - news)

* Tullow, Weir renew oil-price linked slide

* Morrison, Ocado rally as retail picture improves

By Alistair Smout

LONDON, March 10 (Reuters) - Britain's top share index edged further from all-time highs on Tuesday, led down by heavyweight Prudential (SES: K6S.SI - news) after the insurer said its CEO was leaving for Credit Suisse.

Prudential dropped 2.6 percent, trimming 4.3 points from the FTSE 100 index as the news that chief executive Tidjane Thiam would leave his post took the shine off an earnings report that analysts said was solid.

"Tidjane's tenure as CEO of Prudential has been characterised by a maturing of Prudential into a worldwide leader in annuities, asset management and savings," Shore Capital (Other OTC: CGHC - news) director Eamonn Flanagan said in a note.

He added the results were excellent and saw "any potential weakness as a buying opportunity," keeping a "buy" rating on the stock.

The FTSE 100 was 0.2 percent lower, down 15.80 points at 6,860.67 points by 0837 GMT, its third consecutive daily fall.

The index is now 1.6 percent below an all-time high of 6,974.26 points hit on March 2.

Tullow Oil (LSE: TLW.L - news) dropped 4.2 percent to its lowest level since June 2006, having lost half its value since September after an oil price slump.

Engineer Weir Group, dropped 2.7 percent, reversing some recent gains. It had rallied nearly 12 percent since Thursday on speculation that the firm, which has been hit by cutbacks in investment by oil firms, might attract interest from U.S. private equity.

Supermarket Wm Morrison rose 3.1 percent ahead of earnings on Thursday, while online grocer Ocado reported a slight acceleration in quarterly sales growth and said it expected to continue growing ahead of the market.

"We see this as an encouraging result against a challenging UK grocery market backdrop," analysts at Numis said in a note.

Morrisons and Ocado have a distribution contract which Ocado said Morrisons was "pretty happy" with. Ocado rose 2 percent.

In an extra boost, British retail spending kept shops busy in what is normally a quiet month in February, suggesting a plunge in inflation has given consumers a boost, an industry survey showed on Tuesday.

G4S (LSE: GFS.L - news) , the world's biggest security group, rose 1.8 percent after posting a bigger than expected rise in 2014 profit even as it said it would increase provisions for under-performing UK government contracts.

(Editing by Catherine Evans)