A 77-year-old woman who has only one meal a day and travels on buses during the day to keep her household bills down was “disappointed” with Boris Johnson’s response to her plight in an interview with Good Morning Britain, the show’s presenter Susanna Reid has said.

The prime minister was challenged by Reid about Elsie’s financial predicament and increasing energy bills on the ITV programme. Johnson, the former London mayor, replied: “The 24-hour freedom bus pass [allowing free bus travel for over-60s in London] was actually something that I actually introduced.”

Speaking to LBC’s Tonight with Andrew Marr about her interview on Tuesday with the prime minister, Reid said: “I’ve spoken to Elsie, since the interview this morning with the prime minister, and she says how disappointed she is with what he said.

“Because she says there are people who are even worse off than she is, and there was no answer for them, apart from ‘oh I was the person who was responsible for the bus pass,’ I mean, as if she’s supposed to be grateful.”

Andrew Marr added: “Which is by the way, not entirely accurate itself because it was the London boroughs who brought that in.”

According to Reid, Elsie’s gas and electricity bill has soared from £17 to £85 a month. She has lost weight after reducing herself to one meal a day and shops only in the late afternoons when price-reduced “yellow sticker” items come on sale.

The prime minister had said to Reid that there were “plenty of things more that we are doing”, adding: “What we want to do is make sure that we have people who are in particular hardship looked after by their councils, so we are putting much more money into local councils.

Pushed on what Elsie should cut back on, he said: “I don’t want Elsie to have to cut back on anything.”

Johnson added: “The best answer is to help her abate the cost of energy as we are, but also … to make sure there’s a direct cut in her council tax as a result of what we’re doing.”

During the interview, the prime minister also highlighted the winter fuel allowance and other “measures that we’ve put in place to help people”.

He said the government is “making sure that we take the steps now to invest in our energy supply” to “ensure that we have the supply for the medium and the long term”.