"I'm in disbelief. I can't believe it's me," she said.

The 68-year-old grandmother of eight found out that she had cleaned up last week, winning $294m (£158.5m), the second largest single ticket win in the US.

A few days later she fully intended to keep an appointment to clean a client's house but reluctantly cancelled when she was told she had to meet financial advisers in Boston. Later she bought two cheap vases at a yard sale.

"That's the kind of person she is," Barry Scanlon, whose father Thomas is Ms Williams' long-time companion, told the Lowell Sun.

"She is one of the most humble, down-to-earth people that I know. They say good things happen to good people. Well, she's a person with a heart of gold."

Friends of Ms Williams, a former college warden with three children, were full of praise.

"She was a wonderful person," Mary Recko, a former colleague at the college, said. "Everybody liked her. All of us here are so happy that it was her who won."

A neighbour described her as a bundle of energy.

Ms Williams, who bought the ticket at an off-licence, was given the choice between receiving the full amount over 26 years before tax or a lump sum of $168m before tax. She chose the lump sum.

The biggest single lottery winner in the world was Jack Whittaker, of West Virginia, who won $314.9m (£173m) in December 2002. He had bought 100 tickets for the lottery draw.