The 83-year-old, who was sacked as a government adviser last week after rebelled over Brexit, did not hold back on the ITV breakfast programme this morning.
Explaining why he was against Brexit, the former deputy prime minister told hosts Piers, 51, and Susanna Reid: “Well, it’s difficult to know where to start. Every prime minister I’ve worked for – and I’ve worked for many – have told us the British will topple without Europe and that our future was completely interwoven with our continental members.
“Companies tell me they want certainty with their biggest market. The younger generation are appalled that they are being cut off without any certainty from a community, the European community and which they feel very happy and know that their future depends.”
Host Piers then asked him: “Do you play cards, Lord Heseltine? Do you play poker? When you play, you show anyone your cards?”
“Let me be clear. I have made it absolutely clear that Theresa May should not reveal her hand. That would be naive,” he said.
Lord Heseltine continued: “Of course the people that want her to do that are the Brexiteers because they’re frightened that there will be some sort of compromise and they want to be able shout loud to stop it happening.
“But the fact is that they’re position is naive in two ways actually. Firstly, they want her to reveal her hand, so they can criticise it. But secondly, they don’t seem to understand it’s not what we want, it’s what the Europeans will give us.”
However, it appeared that Piers Morgan was not impressed with his answer and told him: “Hang on, hang on this sounds incredibly defeatist for a man of your stature, rolling over and letting the Europeans decide.”
“They won’t determine how we go forward but they will on the terms,” he hit back.
He added: “The idea that they will let us go out and set a precedent that will create a domino effect will simply not happen.”
The fierce clash on Good Morning Britain between the pair comes ahead of the government deciding on changes to the proposed Brexit bill made in the House of Lords.
It is believed that MPs will reject the amendments made by peers which would guarantee the rights of EU citizens in the UK.
The prime minister could trigger Article 50 as early as tomorrow and begin the process of Brexit.
Good Morning Britain airs weekdays on ITV at 6am.