The set is said to be the most comprehensive ever sold and comes complete with pristine model boxes.

In some cases the boxes will be worth more than the toy cars or trucks inside – though one rare green and yellow No13 wreck truck model is estimated to fetch up to £6,000.

Auctioneers Vectis said the Ameri­can owner had put together “the most comprehensive collection ever to be sold and which may never be equalled”.

It goes under the hammer in Middlesbrough in September.

Andrew Reed of Vectis, who flew to the US to pick up the cars, said the models were “exceptional”, with some versions worth thousands of pounds.

The £500,000 collection

He said the owner, Dr Scott D Gillogly of Atlanta, Georgia, started collecting as a child and revived the habit in later years when it reminded him of “simpler times”.

But now his collection is complete he wants to sell it. “He just feels that the chase is over and he has collected as many variations as he can,” said Mr Reed. “He is coming towards his mid-50s and he just wants to sell.”

And it seems he has made a sound investment over the years.

Mr Reed said: “Over the last 10 years you have probably seen 10 per cent to 15 per cent average growth each year. You would never make that kind of money in the bank.”