BUZZ-Babcock: Warns on first-half oil and gas revenue
** Engineering and support services firm's shares down 3.8 pct, top FTSE-100 loser, after warning revenue from oil and gas would be lower in H1
** Co said revenue from oil and gas in its high-margin MCS unit would see a "low double digit decline" in H1
** Unsuccessful bid to provide services for French firefighting fleet also weighing, analysts say
** Worst day for stock in 5 months, which is also the top loser on the Stoxx 600 Industrial Goods and Services index
** Stock now at 2-mth lows, with 73 pct of its 30-day avg volume going through in the first two hours of trade (venkateshasoumithri.mamidipudi.thomsonreuters.com@reuters.net)