The veteran banker, who had sought a major investor to lend a suitably Scottish name to his Scoban venture, has attracted insurance and financial services group Hampden, the largest priv-ate capital adviser at Lloyds.
Like Scotland's national stadium, the finance group is named after 17th century English reformer John Hampden. It will now take a "significant" stake in Sco-ban, and is likely to introduce Lloyds members - some of the UK's highest-rollers - as clients.
Mr Entwistle said initial discussions with Hampden had begun two years ago.
"It is a very exciting development for us to have a company such as Hampden taking a significant investment in our new bank," he said. "Hampden is a fantastic business with a successful track record in different fields."
He added: "We are now talking to a number of interested parties, good quality organisations that want to be associated with the new private bank.
"Hampden does look after a lot of very important people, we know a number of their clients will also be interested in becoming investors - people who underwrite at Lloyds are usually fairly well-placed financially and there have been one or two very good years. We feel we are going to be able to add to each others' businesses."
Mr Entwistle launched Scoban in 2011 and last month it became the first new bank to be granted a licence under the Prudential Regulation Authority's 'mobilisation' process. The bank will open its doors as Hampden & Co, in Charlotte Square and St James's, London, later this year.
Tim Oliver, chairman of Hampden, said: "We have invested in Scoban since its inception as we believe that there are great opportunities for a new private bank in the UK. I am delighted that we have reached an agreement for the new venture to be launched under the Hampden name."
Mr Entwistle added: "This is important because it gives us our branding for the future. We are quite pleased with the name, Scoban was picked off the shelf back in 2010 to see us through until we found the right one."