The director of a Scottish educational charity that is world-renowned has resigned after a failed lottery bid led to plans for a £1.6m new headquarters being scrapped.

Dr David Munro had secured £500,000 to help pay for the Royal Scottish Geographical Society to move from cramped, fifth-floor rooms in a Strathclyde University building in Glasgow to two neighbouring historic buildings 60 miles away in Perth.

The aim was to create a "world-class" base by leasing the Fair Maid's House and buying Lord John Murray's House next door, allowing the public unprecedented access to the society's archives and maps charting the achievements of Scottish explorers.

However, following a failure to net £600,000 from the Heritage Lottery Fund, the society's council decided to come up with a new plan aimed at carrying out most of the original project but "in phases" and at around "half the cost". As a result, the original architect was dismissed and planning permission, listed-building consent and most of the funding pledged for the initial scheme have been lost.

The society council's interim chairman Barrie Brown admitted that despite the lease on its current base in George Street, Glasgow, running out in September, the new scheme was still not fully costed or funded but he stressed it was backed by Perth and Kinross Council and he was confident that money would come in.

Explaining why he left his post after 12 years, Dr Munro said: "We had prepared a very robust plan to acquire and rent the buildings in Perth but having raised more or less single-handedly half a million in cash or grant offers, the Heritage Lottery Fund then turned down the bid and the society's council made the decision to start taking the plan apart.

"I really believe if we had pushed on we could have raised the money in the necessary time, which would have given the society a world-class home - but they got cold feet.

"I had to go back to funders and tell them there was now a totally new plan. I do not think the society council's plan B is workable. They are not delivering a building that I think is fit for purpose and I don't think that funders will fund it."

Yesterday, Mr Brown said it was "quite a blow" not to get the lottery cash and the society's council decided to "re-cut the coat according to the cloth". He said the society's council already had £300,000 from the society's own funds to transform the Lord John Murray building into a new HQ, which was expected to be ready by early September.

At a later stage it hoped to refurbish Fair Maid's House to create an exhibition space and then design a new storage space, but had yet to secure any money. Perth and Kinross Council said it stood by its offer to lease Fair Maid's House and said the scheme was "largely unchanged".