Capital MD Steffan Williams said he hoped the appointment would allow Capital, whose financial comms clients have traditionally been European companies, to position itself as adviser to firms wanting to list on the UK's fashionable AIM.
After qualifying as a solicitor, Curtain spent 14 years as a business journalist before moving into PR. He was business editor of The Yorkshire Post between 1995 and 2000 before joining Business AM, where he was City editor for one year before taking a role at Bankside.
He will work on UK clients at Capital, including NXT and Torotrak.
Curtain's appointment came as the London Stock Exchange signalled a move to court more European companies for the AIM, whose lower level of regulation, and therefore cheaper compliance, have proved
attractive to companies over the past few years.
The LSE has come under pressure from Nordic-Baltic exchange OMX, which has announced plans to create a small-cap market by the middle of next year. It intends to copy the success of AIM, and ultimately to compete with it.
More than 389 companies have floated on AIM so far this year, up from the 356 new listings on the index in 2004. Having begun ten years ago as a type of introductory index for smaller companies not yet ready for a full LSE listing, AIM is now home to companies with a collective market capitalisation of around £50bn in 33 sectors.
The index's lighter-touch regulation and cheaper compliance costs have even persuaded companies such as Next Fifteen Communications to move from the LSE to AIM.
Capital's move will put it more directly in competition with agencies such as Abchurch and Buchanan Communications.
Correction: Torotrak and NXT are not moving to AIM as stated in earlier versions of this article