He will report to M co-founders Nick Miles and Hugh Morrisson, and will take equity in the company. 'Ed is taking a generalist role but has great experience in industrials, utilities and telecoms,' said Miles.
Finsbury partner James Murgatroyd said: 'Ed will be well suited to life at M and we wish him well.'
Orlebar's clients at Finsbury included German utility firm Eon, which last year bid £19.9bn for Spanish gas and electricity supplier Endesa. He became Finsbury's fourth director when he joined the agency in 1999, teaming up with Rupert Younger, Murgatroyd and founder Roland Rudd.
He was previously a reporter on the Bloomberg UK companies desk.
This week, M secured a contract to become the UK corporate agency for transport company Sea Containers. Miles leads the account, reporting to trouble-shooting CEO Bob MacKenzie, who joined the embattled firm in January.
The M team will also work with Sea Containers director of comms Lisa Barnard.
Sea Containers, which owns train operator GNER, this month invited all 235 of its London-based staff to apply for voluntary redundancy as part of an urgent cost-cutting exercise. In March it said GNER was undershooting its revenue targets due to the effect of the July 2005 London bombings on passenger numbers.
The Bermuda-registered company currently has around £700m of debt.
MacKenzie previously used Miles while chairman of the National Parking