The men who flew the aircraft and responded to the call to defend Britain in the air were a mixed bag.
"In terms of numbers, there were the Brits, clearly, then there were the Poles, and then there were New Zealanders.
"Keith Park was the key player in that battle. I say that because at that stage the continent had gone [defeated by Germany], he [Hitler] hadn't started into Russia — he still had his agreement with that, America wasn't in the war.
"There was great groundswell within the Brits, at senior levels, to do a deal with Hitler. Many of them, Lord Beaverbrook and others, thought Churchill was a warmonger."
Graeme says The Battle of Britain was crucial.
"Had that battle been lost there's no doubt they would have done a deal with Germany. That would have put New Zealand out of the war, clearly, it would have put Australia and Canada out of the war. We weren't going to take on Germany from afar if Britain wasn't there.
"The Americans could not have invaded the continent from America."
They needed Britain as a base. Just after the Battle of Britain, Germany invaded Russia.
"Russia was collapsing: they got a whole bunch of aid from Britain and America which enabled them to hold on until winter set in."
If Britain was out of the war, having lost the Battle of Britain, there would have been no such aid.
"Probably, Hitler would not have had to have had divisions in the Middle East: he wouldn't have had to worry about those fronts. He would have needed divisions in France in case Britain did something — he could have put the whole lot against Russia and, no doubt, would have steamrolled them."
This was the most important battle, says Graeme. Had it been lost, England would have gone, America would not have entered the war and history would have had a very different author.
"As New Zealanders, as time has gone on, we have naturally moved away from Britain, so the title, 'The Battle of Britain', is becoming less important. But, to me, it's crucial.
"It was Keith Park's brilliance, how he handled his fighters."
Britain's air capability was split up — 11 Group looked after London and the southeast; 10 Group looked after the west; 12 Group sat above the top; and 13 Group up by Scotland and the far north.
It was 11 Group that was commanded by New Zealander Keith Park who kept sending up fresh, fully fuelled fighters to harry the German planes at the limit of their range. Keith Park's tactics proved a vital, winning component in the long-running battle.
"It was a New Zealander that did that, and it's only in recent years that it has been recognised that he actually won The Battle of Britain.
"That is why we don't lose sight of the value of The Battle of Britain and the value of the New Zealand input in it. It was that important."