Britain's FTSE sets fresh record high; Dixons, Next rally

* FTSE 100 up 0.4 pct, sets fresh all-time high

* Dixons Carphone (LSE: DC.L - news) gains after selling German chain

* AstraZeneca (NYSE: AZN - news) boosted as medicine gains orphan status in U.S.

* Next (Other OTC: NXGPF - news) boosted by JPMorgan (LSE: JPIU.L - news) upgrade ahead of update

By Francesco Canepa

LONDON, April 15 (Reuters) - Britain's top share index hit a fresh all-time high on Wednesday, helped by gains in fashion chain Next, retailer Dixons Carphone and drugs firm AstraZeneca.

Fashion chain Next rose 2.5 percent to the top of the FTSE 100 after JPMorgan upgraded the shares to "overweight" from "neutral" ahead of the company's update on April 29.

"We think that the more favourable weather since Next last updated the market on 19th March, assisted by the favourable UK consumer background, should have led to stronger trading in the second half of (the quarter)," JPMorgan analysts said in a note.

Dixons Carphone, the electricals and mobile phone retailer, was up 1.8 percent after German mobile telephone company Drillisch agreed to buy the UK firm's telecoms shop chain The Phone House Deutschland for a combination of shares and future cash flows.

AstraZeneca gained 1.8 percent after one of its experimental medicines that helps the immune system fight tumours won "orphan" drug status in the United States, meaning it would enjoy seven years of marketing exclusivity.

Precious metals miner Fresnillo (Other OTC: FNLPF - news) rose 1.3 percent after saying it was on track to achieve its 2015 production guidance and reporting higher output in the first quarter.

Luxury brand Burberry added as much as 2.8 percent before paring gains after it posted a 9 percent rise in second-half underlying sales.

The FTSE 100 was up 0.4 percent at 7,101.24 points, after briefly setting a new all-time high at 7,104.25 points.

The index's rally has so far been largely unaffected by uncertainty surrounding Britain's election on May 7, when no party is expected to win an outright majority.

Yet some traders suspected this might change as election day approaches.

"We've been taking profit in the last week or so," Mark Ward, head of execution trading at Sanlam Securities UK, said.

"We've got the general election coming up in the next few weeks and ahead of that we might see the FTSE hang up here." (Editing by Susan Fenton)