UPDATE 1-Tesco completes $5.5 bln takeover of Booker?

* Booker shares de-listed

* Integration of Tesco and Booker to begin

* Takeover approved by court on Friday

* Investors backed deal on Wednesday(Adds detail)

LONDON, March 5 (Reuters) - Tesco's 4 billion pound($5.51 billion) takeover of Booker has completed, bothcompanies said on Monday, creating a new powerhouse in Britain's200 billion pound-a-year food market.

The cash and shares deal to combine Tesco, Britain's biggestretailer, with Booker, the country's largest wholesaler,received court approval on Friday and is now in effect.

The deal received regulatory approval in December and bothsets of shareholders backed the plan last Wednesday.

Booker shares have now been de-listed from the London StockExchange. For each Booker share Tesco offered 0.861 new Tescoshares and 42.6 pence in cash. Tesco shares closed Friday at 202pence.

Analysts noted that with a market capitalisation of justunder 20 billion pounds, Tesco is now bigger than the whole ofrivals Sainsbury's, Morrisons, Marks & Spencerand Ocado put together.

Tesco will now start its "Joining Forces" programme tointegrate the two businesses.

Charles Wilson, formerly Booker's chief executive, takesover as CEO of Tesco's retail and wholesale operations in the UKand Ireland reporting to group CEO Dave Lewis.

Stewart Gilliland, formerly Booker chairman, will become anon-executive director of Tesco.

($1 = 0.7254 pounds)(Reporting by James Davey; editing by Sarah Young and JasonNeely)