Harris said the time was right for her to “look for a new challenge” after being with the LBG intermediary business for six years and the group for much longer.
An LBG spokeswoman said the changes were the final stage in creating an “entirely intermediary focused division within the Lloyds group”.
Curran returns from secondment at the Lloyds TSB branch network to take up a new role as director of strategic partnership management and national accounts.
He will be responsible for national accounts, proposition development, housing development and campaign management. He will also deputise for the director of intermediaries where necessary.
Ian Wilson, head of sales at Halifax Intermediaries, and Phil Rickards, head of sales at BM Solutions, will remain in their current roles within the new business and report to Mike Jones, who will also remain as interim director of intermediaries.
Jones said: “The changes that we've announced today to the intermediaries business show that we're in the best place to drive this business forward.
“The new leadership team and I are dedicated to ensuring that the intermediary is right at the centre of everything we do, and I look forward to sharing more of our plans in the coming months.
“I wish Maria Harris all the very best as she leaves the group to take on new opportunities. She has been a tremendous member of the team, and has taken the national accounts team from strength to strength.
“Over the next three months, Maria will help us deliver our new strategy. She'll be a real loss to us and I'm sure will be a great success in future opportunities. "
Maria Harris added: “The shape of the intermediary structure is changing for the better. I wish Mike's new team every success as they move forward, and feel that now is the right time for me to look for a new challenge.
“The intermediary market is a great place to work. I've really enjoyed my time with the group and have made a lot of friends along the way.”
