Ms Glenn is worried the owner of the building, a property specialist with large-scale commercial, industrial and retail leasing expertise, does not want to keep the name Gus'.

Known as Gus' since the 1960s, and where owner Gus Petersilka introduced outdoor dining in the 1970s, the Garema Place landmark opposite the Canberra Centre, closed about a month ago. The building's owner, Certrane Pty Ltd, did not renew Ms Glenn's lease.

Ms Glenn says she has never met her landlord, had only dealt with property managers and lawyers, but now was exchanging emails with Certrane's principal John Grimble.

Mr Grimble said he had not made a decision on Gus' name, and was seeking more information from investors.

Ms Glenn's family spent more than $100,000 on the dining area outside Gus' on the footpath, with a timber sash window enclosure. This area is leased to her by the ACT government, although she is unsure what its future will be because it is dependent on the building's cafe equipment.

Her family bought Gus' cafe business about 1994 and her mother Setita Rockmann later lobbied to get it heritage-listed. Ms Glenn said Certrane bought Gus' building in 2007. The heritage listing was granted in 2011, but what that listing means is unclear.

The listing says Gus' Cafe is an example of one of Canberra's cultural heritage places, illustrating intangible heritage values. It is not the physical fabric of the building that represents its heritage value. It is the history of the place and the activity there over many years that gives the Gus' Cafe site its strong historic cultural and social heritage significance for the local community.

"I was under the impression it would continue to be Gus', but I am unsure now," Ms Glenn said.

The ACT Heritage Council told her it was a grey area. "I thought it was the name that was heritage-listed, [but] that's not the case. They can only strongly suggest that it be retained. I don't understand why it is just the plaque. It has something to do with legalities. The owner of the building objected."

Ms Glenn said Sydney investors may not understand Gus' cultural significance. "It doesn't matter who goes in there, so long as it is Gus', that's what I would like to focus on," she said. "There are so many memories there for a lot of people."

Negotiating her departure, she was assured new lessees would continue the cafe business and employ some of her staff. "They were, 'Yes, yes, let's have a look at it'. I took that as a definite, and that they were going to continue with some of our staff. I am sad they are not considering, or seeing the importance of this."

Ms Glenn said she was told no precedent existed for the heritage listing. "But that is the story of Gus's life, he was always the first to do things," she said.

"Canberra is a new city, and when you have something of that significance how can you honour it? I want to make this a win-win outcome for everyone. Certrane's resistance doesn't make sense to me," she said.

"People leave Canberra and return 20 years later and say Gus' is their only point of reference. I'm being told that all the time."