UPDATE 2-Britain's Ocado could make early start to M&S deliveries

* Ocado-M&S venture due to start deliveries September 2020

* Earlier start a possibility -Ocado finance chief

* Ocado Retail third-quarter revenue up 11.4%
(Recasts with Ocado finance chief's comments, share price)

LONDON, Sept 17 (Reuters) - British online supermarket Ocado
could start home deliveries of the full Marks & Spencer
range before next September, ahead of their joint
venture's original deadline, it said on Tuesday.

Ocado and M&S completed the 1.5 billion pound ($1.9 billion)
joint venture deal in August, creating Ocado Retail and
signalling the end of Ocado's supply contract with upmarket
supermarket chain Waitrose in September 2020.

"There is a chance we might bring forward, at least
partially bring forward, that transition date," Ocado finance
chief Duncan Tatton-Brown told reporters.

But he said that would require the agreement of all three
parties.

"It may well be in the interests of Waitrose, some of
Waitrose's suppliers and ourselves and M&S for that transition
to be slightly more spread out," he said.

M&S declined to comment while Waitrose, part of the
employee-owned John Lewis Partnership, had no
immediate comment.

Ocado also reported an acceleration in retail sales growth
in its third quarter, helped by additional capacity from its
fourth automated warehouse.

For the 13 weeks to Sept. 1, Ocado retail revenue rose 11.4%
to 386.3 million pounds, compared with first half growth of 9.7%
and guidance of 10-15% growth for the second half.

Average orders per week rose 12.1% to 314,000 as more slots
became available, though average order size fell 0.8% to 105.42
pounds, reflecting a slightly higher frequency of purchases.

In February Ocado warned that sales growth would be dented
until it increased capacity elsewhere after a fire devastated
its flagship robotic warehouse in Andover, southern England.

That extra capacity was secured through a deal with
Morrisons, Britain's fourth-biggest supermarket group,
in May to allow Ocado to take back sole use of its fourth
robotic warehouse in Erith, southeast London.

"This first set of results from the joint venture between
Ocado Group and M&S show the resilience of Ocado following the
Andover fire and the momentum the business now has," said Ocado
Retail CEO Melanie Smith.

Shares in Ocado were up 1.2% by 0845 GMT, taking
year-on-year gains to 50%.

While Ocado's retail business holds only a 1.4% share of
Britain's grocery market, its warehouse technology has powered
the group's 9.5 billion pound stock market valuation.

Ocado has technology deals with eight major retailers,
including U.S. group Kroger and France's Casino
.
(Reporting by James Davey
Editing by Paul Sandle and David Goodman)