Last checked at 
* FTSE 100 up 0.1 pct, FTSE 250 0.5 pct higher
* Both reverse course after earlier losses
* Oil majors biggest boost
* Small-cap Ophir Energy skyrockets on takeover talks(Adds analyst comments, updates share moves)
By Muvija M and Shashwat Awasthi
Jan 2 (Reuters) - British shares clawed back losses onWednesday to end the year's first trading day on a positive noteafter a disastrous 2018, helped by investor appetite for stocksdeemed less risky and also by a comeback for oil majors despiteweak data from China.
London's blue-chip bourse ended 0.1 percent higherwhile the mid-cap index was up 0.5 percent after steeplosses earlier on Wednesday.
The indexes teetered as trading volumes remained roughlyaround two-thirds of their 90-day average during the session,after recording their worst yearly drop since the 2008 financialcrisis last year.
Heavyweights BP and Shell advanced 2.3percent and 1.4 percent, respectively, as crude prices erasedearlier losses to trade in the black.
Investors also took some notice of the positive domestic PMIdata prompted by Brexit-induced stockpiling, althoughuninspiring Chinese data had sparked a global sell-off earlierand raised questions about the global economy.
"Although stockpiling played a role in the strong UK PMIdata, it was still the best economic news out there today," saidJasper Lawler, head of research at London Capital Group.
Defensive stocks - considered less risky - also offeredsupport to the main index, with shares in telecommunicationfirms, healthcare companies and utilities all gaining.
GLOBAL WORRIES
Manufacturing activity in China, the world's second-largesteconomy, contracted for the first time in 19 months amid itstrade spat with the United States. That comes on the heels of apoor official survey on factory output on Monday.
U.S. manufacturing activity also fell, data showed, whilethat in the euro zone barely expanded in December.
Continued fears of a global cyclical downturn will likelycap the upside for blue-chip British shares, said CMC Marketsanalyst Margaret Yang.
"A string of missing PMIs from China's official and privatesector suggest that Asia's largest economy is still cooling offdue to weaker external demand and trade uncertainties," Yangsaid.
"It is still too early to say markets have bottomed outyet."
A drop in sterling, with strong factory surveys failing todispel growing anxiety over the Brexit negotiations, lifted theshares of companies that book in revenue from the United States.
Pharmaceutical giants GlaxoSmithKline andAstraZeneca pushed out modest gains while consumer giantUnilever rose 0.8 percent.
Financial heavyweights Prudential and Lloydsfell nearly 2 percent each.
Investors also shunned miners due to the concerns overgrowth in China, which is the world's top metals consumer, andinstead turned to safe haven commodities. Gold prices rose to amore than six-month peak as a result, pushing Fresnillo3.3 percent higher.
Glencore, Antofagasta, BHP, AngloAmerican and Rio Tinto edged 1.1-3 percentlower.
High street retailer Next Plc was up 4.7 percent,top of the blue-chips, ahead of its Christmas trading update dueon Thursday.
John Lewis' higher sales in the week ending Dec. 29 was aray of sunshine for a retail sector buffeted by competition fromAmazon, by Brexit jitters, lower consumer spending and risinglabour costs.
John Lewis, which is Britain's biggest department storesoperator and the first retailer to update on trading atyear-end, said demand had been "very strong" on Christmas Eve.
Medical products maker Smith & Nephew tumbled 2.4percent, with traders citing a rating cut by brokerage JPMorgan.
Among the midcaps, Energean Oil & Gas added 4.3percent after signing a gas supply agreement with independentpower producer I.P.M. Beer Tuvia.
Elsewhere in corporate news, Ophir Energy soarednearly 30 percent to the top of the small-cap indexafter the oil and gas producer said it was in takeover talks.
Real estate investment trust Hammerson fell 2.1percent as it said its share buyback program will be pausedahead of the release of 2018 results.
(Reporting by Muvija M and Shashwat Awasthi in BengaluruEditing by Gareth Jones)
