UPDATE 2-UK shares gain on vaccine hopes; Ladbrokes owner soars

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* UK's FTSE 100 gains most in four weeks
* Plumbing parts maker Ferguson sells UK business
* Miner Rio Tinto biggest gainer in FTSE 100
* FTSE 100 up 1.7%, FTSE 250 adds 0.2%

(Updates to market close, adds analyst comments)
By Shashank Nayar and Shivani Kumaresan
Jan 4 (Reuters) - British shares closed higher on Monday in
the first trading session of the new year, buoyed by optimism
around vaccine rollouts, while a jump in metal prices helped
boost the export-heavy FTSE 100 index.
The blue-chip index .FTSE rose 1.7% on its first day of
trading with Britain outside the European Union's orbit, with
shares of Entain ENT.L the top gainer.
The Ladbrokes owner surged 25.3% to an all-time high after
saying it received proposals from U.S. casino operator MGM
Resorts MGM.N for a possible offer. "We are seeing optimism on the first day trading on the back
of a very positive month of December in which a collection of
major risk events such as the Brexit deal and vaccine approval
went in the right direction," said Craig Erlam, senior market
analyst at OANDA.
Mining shares .FTNMX1770 and consumer stocks were among
the top gainers, with Rio Tinto RIO.L giving the biggest boost
to the index. Unilever ULVR.L and Reckitt Benckiser Group
RB.L advanced between 1.5% and 3.6%.
The mid-cap index .FTMC jumped 0.2%.
However, limiting gains was Prime Minister Boris Johnson's
warning that tougher lockdown restrictions were probably on the
way as COVID-19 cases keep rising. "The near-term risks from this ferocious wave of COVID that
we are seeing may be a drag on sentiment in near term," Erlam
said.
Analysts at Deutsche Bank say markets would now be closely
watching any issues with COVID-19 or the vaccine rollout, given
that the new coronavirus variants, found in the UK and South
Africa, have been detected in several other countries.
Drugmaker AstraZeneca AZN.L jumped 1.3% after Britain
became the first country to roll out its low-cost and easily
transportable COVID-19 vaccine, the second vaccine candidate to
be distributed.