The future of one of Scotland's finest examples of 19th-century commercial architecture has become a little more hopeful after it emerged that the potential developer could be in line for a £5 million grant.

The Egyptian Halls in Glasgow, designed by Alexander "Greek" Thomson - one of Scotland's most important and distinctive architects - has been largely disused for almost 30 years.

For over a decade, Dundee-based property developer Derek Souter, who owns the building, has wanted to redevelop the dilapidated category A-listed building opposite the side entrance to Central Station.

Until recently, the Heritage Lottery Fund (HLF) did not provide grants to commercial projects but the fund's Heritage Enterprise programme, launched last year, aims to finance the redevelopment of neglected historic buildings and "unlock their economic potential".

Grants cannot be paid to for-profit companies so a newly created trust, the Egyptian Halls Building Preservation Trust headed by Martyn Roe, a respected property industry figure, was created and it submitted an application for funding at the end of June. A decision is expected next spring.

The proposal, which received planning permission from Glasgow City Council in 2012, would see the upper three floors of the building converted into a 114-bedroom four-star hotel with a two-storey extension and the refurbishment of four ground-floor shops.

But red tape and a funding shortfall meant that building work on the £20m project never got under way.

Although Historic Scotland has offered a grant of £1.65m towards the project, a time-limited £1m grant approved by Glasgow City Council in May 2010 lapsed in March 2011. Historic Scotland, meanwhile, claims that it cannot offer a larger grant for a commercial project.

Souter said that the approval of a £5m grant from HLF, the maximum possible under the Heritage Enterprise programme, would be a "game-changer" for the stalled redevelopment project. But it would still leave a funding shortfall of around £5m.

At a public meeting on Wednesday, Souter said it would also be unsafe to comply with Glasgow City Council's request for the scaffolding on the building, which has been in place since 2009, to be taken down. A piece of masonry "the size of a large man's fist" that fell from the building's facade this week could have killed someone had it not been for the scaffolding, he warned.

The feasibility of installing CCTV cameras is now being considered in response to tenant concerns that the sheltered pavement area beneath the scaffolding is attracting beggars, pick-pockets and drug dealers.

Souter - who has invested £6.2m in the project since 1998 - said the completed project would be a catalyst for the regeneration of Union Street, once one of the top retail streets in Glasgow. This would lead to investment in the area, the creation of new jobs and £350,000 in business rates each year for the public purse, he claimed.

Asked whether Glasgow City Council would consider renewing or making a fresh offer of grant assistance in the event of an HLF grant being approved, a spokesman said: "We cannot speculate on any prospective HLF funding, and this is not relevant to the current position."