Speaking on the BBC Radio 4's World At One after the Tories secured a deal with the DUP to prop up the Government, Lord Heseltine said: "I'm reminded of Enoch Powell's phrase: 'Once you have paid the Danegeld, you never get rid of the Dane.'
"This is not a long term solution because even adding the DUP votes to the Tory votes there is still the risk of lost by-elections eroding the majority."
When he was asked about Theresa May's claim the deal with the DUP would provide "certainty" during Brexit negotiations, the former deputy to John Major said she was wrong.
"Yes, that’s what she does say. And of course it’s completely devoid of reality, because there is no such unity on this issue.
"There is a deeply divided country and every day, either within the cabinet, within the leaders of the industrial world, within the academic world, more and more people realise the consequences [of Brexit]."
The 84-year-old added: "This is a deeply divided country and singling out one part of it in order to give a semblance of short term stability is just one more of the prices we're paying for the consequences of Brexit.
"I think it will take two years, 18 months, for the Government to be at risk, and that's assuming they can command the loyalty in the Brexit confrontations of every Conservative MP. That is by no means certain."
Lord Heseltine previously warned the electoral base is dying off at a rate of 2 per cent per year and called for a new party leader.
He said the party needs to work hard to “restore its electoral fortunes” and that Ms May should step down after a “matter of months”.
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