Commods drive 1.5 pct FTSE bounce as Q3 kicks off

* Commodity prices lift miners, energy stocks

* Broad based rally as Q3 gets underway * Marks & Spencer up on trading news

By Simon Falush

LONDON, July 1 (Reuters) - Robust commodity prices boosted energy and mining stocks which led a broad-based rally at the start of the third quarter, lifting Britain's top share index 1.4 percent higher by midsession on Wednesday.

Crude rose nearly 2 percent to above $71 per barrel CLc1 fuelling a rise in heavyweight energy stocks, which added most points to the index.

BP (BP.L: Quote, Profile, Research), Royal Dutch Shell (RDSa.L: Quote, Profile, Research), BG Group (BG.L: Quote, Profile, Research), Tullow Oil (TLW.L: Quote, Profile, Research) added between 1.2 and 3.1 percent.

By 1027 GMT the FTSE 100 .FTSE was up 62.45 points at 4,311.66, after closing 44.82 points, or 1 percent, lower on Tuesday at 4,249.21.

The index ended up 8.2 percent on the quarter, the best such performance since the final quarter of 2003, and has gained 22.8 percent since touching a six-year low on March 9.