Hammond Suddards' online legal advice service has won the contract to advise Virgin One.
HammondsDirect offers legal support for clients outside working hours via the internet.
Virgin One is a subsidiary of Virgin and offers bank accounts that incorporate a client's mortgage.
HammondsDirect will handle legal issues connected to re-mortgages from people switching lenders to Virgin One's new type of account.
A spokesman says it will operate “a virtual department of Virgin One”.
Lucci Dammone, chief executive of HammondsDirect, says the real significance of the new account is that it may lead to advising more Virgin subsidiary companies, especially Virgin Financial Services.
Dammone says: “We are not advising Virgin Financial Services now but we will develop that relationship.”
Virgin Financial Services offers a number of services, including pensions, personal equity plans and individual savings accounts.
Dammone adds: “It is early days yet but Virgin has a whole host of other activities, such as Virgin Atlantic, Virgin coke and Virgin trains.
“We may not get all of these accounts but it is something to target.”