A number of volunteers have resigned over a dispute with the organisation, but one volunteer, who does not wish to be named, fears the shop could close as a result.

The Old Umbrella Shop has 85 volunteers, with each committing to half a day service per month.

"I think the shop could close if they don't have enough people who can volunteer," the volunteer said.

"It was one of the few profitable things [at National Trust], because it was run by volunteers."

IN OTHER NEWS:

In trying to change the way the organisation operates to reflect its "duty of care obligation", National Trust Volunteer Engagement coordinator Wayne Bailey-Walford asked the shop's volunteers to sign an agreement.

Mr Bailey-Walford said the volunteer agreement had been rolled out statewide over six months and "has been endorsed by Volunteering Tasmania as best practice volunteer management, for the safety and welfare of all the National Trust Tasmania volunteers".

While this agreement has many standard clauses dealing with volunteer conduct, dress and approach to their service within the shop, there was one clause on page 11 that struck a group of volunteers as unfair.

This clause requires volunteers to "...accept responsibility for health and safety of oneself, co-workers, volunteers, visitors and anyone who may visit a National Trust Tasmania property..."

Several volunteers, with more than 70 years between them, refused to sign the agreement because they felt they should not have to take responsibility for everyone who came into the shop.

"We've never had any problems in all those years," the volunteer said.

Two volunteers have resigned, Mr Bailey-Walford said, but the volunteer said there were more to follow.

"...there have been a small minority who are not willing to sign the volunteer agreement and have subsequently left the National Trust volunteer workforce. They do not represent the 400-strong volunteers of the National Trust, nor has their departure had any impact on daily operations at site level," he said.

"This small group have [taken] umbrage with the National Trust who is obligated by law to have such an agreement in place."

National Trust Tasmania is holding volunteer information sessions and fortnightly meetings with The Old Umbrella Shop working group to discuss volunteer concerns and questions, Mr Bailey-Walford said.

"The National trust continues to engage volunteers who have happily signed the volunteer agreement and see the value of the document as a tool to responsibly engage and manage volunteers," he said.

The Old Umbrella Shop was previously operated by the Shott family, who made and repaired umbrellas, and continues to sell umbrellas, as well as National Trust and Tasmanian-made products.