flagship

フランスで憲法会議が開かれ、最高所得税率の７５％への引き上げが違憲と判断され却下されました。
French 75% income tax struck down by constitutional council
France's constitutional council has struck down a top income tax rate of 75% introduced by Socialist President Francois Hollande.
Raising taxes for those earning more than 1m euros (£817,400) has been a flagship policy for Mr Hollande.
The policy angered France's business community and prompted some wealthy citizens to say they would emigrate.
Mr Hollande's government said it would rework the tax, due to take effect in 2013, to meet the council's complaints.
In its ruling on Saturday, the Constitutional Council said the new tax rate "failed to recognise equality before public burdens" because, unlike other forms of income tax, it was to be applied to individuals rather than households.
http://www.bbc.co.uk/news/world-europe-20864114

flagshipは文字の通り「旗艦、将官艇」 （『ジーニアス英和辞典　第３版』大修館）という意味の他に「(ホテル・会社・製品などで)最も重要な[よい]もの」という意味(ibid)もあります。Wiktionaryにも"The most important one out of a related group."とありました。
また、Flagship (broadcasting)で「キー局[日本の民間放送（民放）における系列（ネットワーク）の中心となる放送局]」(Weblio辞書)も表すようです。
他にも調べてみたところ、flagship shopで「旗艦店。服飾など小売業の系列店で、中心的存在の本店、またはそれに準じた店舗。」(goo辞書)と載っていました。ビジネス用語でたくさん出てくる単語なのでしっかりおさえておきたいです。(Hatahata)