* FTSE 100 down 0.5 pct
* FTSE 250 down 0.8 pct
* Financials, housebuilders slip after Brexit delay request
* Miners fall on oversupply concerns
* Kingfisher down after results, CEO change plan
* Inmarsat jumps on go-private talks
* Kier skids after results, dividend cut (Adds news items, analyst comment, updates to closing prices)By Shashwat Awasthi and Yadarisa ShabongMarch 20 (Reuters) - Financial stocks and housebuildersslipped after British Prime Minister Theresa May asked theEuropean Union to delay Brexit and caused the FTSE 100 to snap aseven-day winning streak, while a slide in sterling pulled themid-cap index lower.However, satellite operator Inmarsat was a bright spot as itsurged on a $3.3 billion takeover approach.The FTSE 100 ended 0.5 percent lower and the FTSE250 gave up 0.8 percent. Ireland's main index ,often considered a barometer of Brexit jitters, fell 0.6percent.Sterling fell sharply after May asked the EU to delay Brexituntil June 30, but a European Commission document seen byReuters said the delay should either be several weeks shorter,to avoid a clash with European elections in May, or extend atleast until the end of the year. "That the EU would then have to unanimously approve therequest - something that isn't a guarantee - is a furthercomplication for the pound to grapple with," said Spreadexanalyst Connor Campbell.An index of banks skidded 0.6 percent and anindex of housebuilders endured their worst day inmore than three weeks to be the biggest drags on the blue-chipindex. Blue-chip homebuilder stocks gave up between 3-4 percent."As long as the issue of a possible extension remainsinconclusive, bank shares should continue to erode the up-ratinginvestors accorded them," said CityIndex analyst Ken Odeluga.The Brexit update added to woes inflicted by miners , which had slipped as iron ore prices plunged inanticipation of increased supply after Vale SA prepared to restart work at its largest iron ore mine.Home improvement retailer Kingfisher shed 6.4percent on its worst day in nearly a year after it reportedlower full-year results and said it had started the process tofind a replacement for its chief executive officer. Investors also awaited the U.S. Federal Reserve's policydecision, in which it is expected to hold interest rates steady,shave the number of hikes projected for the rest of the year,and detail a plan to end the monthly reduction of its balancesheet. Mid-cap satellite operator Inmarsat jumped 13.1percent on its best day since June 2018 after it confirmedtakeover talks with a consortium of investors that could takethe company private for about $3.3 billion. Automotive fluid storage company TI Fluid Systems scaled up 12.1 percent, its biggest one-day gain on record, asstrong orders boosted annual revenue. But Keir Group tumbled 11.3 percent after itshalf-year underlying earnings fell and the builder slashed itsinterim dividend. (Reporting by Shashwat Awasthi and Yadarisa Shabong inBengaluru; Editing by Gareth Jones)