However, in an interview today he admitted it had been hard to let go of the things he had hoped to do in office by resigning rather than staying on until 2020.
"Yes, it is but at some point you have to let go. It's inevitable in this business. And if you have the opportunity to choose the time at which you do that, then you should take that opportunity.
"It's nice to be able to leave at a time when you're credible. I know what it's like to lack credibility as a politician and it's pretty unpleasant. So it seemed to me that what would work best for the party is the same as what worked best in the transition from John Key.
"That is a leader who had strong support in caucus making their own decision to go and then a positive environment to choose a new leader because they want to – not just because their last one ran out."
English's announcement caught many MPs by surprise. English said he made his decision at Christmas and decided to go quickly rather than stay on longer.
"I thought that it would be too difficult to do the job properly if I'd half left the building. That wouldn't help the party, it would probably end up creating more speculation about leadership or whatever.
"So I thought that once I'd decided for myself then I was better to go."
English also revealed what job he would like in the future:
"Actually, I've always wanted to drive one of those self-propelled silage choppers. I used to love driving big machinery when I was farming. So maybe one of my nephews will offer me a job doing that."
On a more serious note, he said at 56 years old he had had no intention of retiring.
"I don't intend to sit round waiting for things to happen. I want to get another life."
He said the 2017 campaign was one of his favourite memories of politics – and he had even surprised himself during the campaign.
"The opportunity for my family to be part of that and the intensity of the public interest and competitiveness of it."
He was confident he was leaving National in good shape and it would remain competitive in the 2020 election.
