Staff aged over 65 at the Longleat tourist attraction in Wiltshire have been made to retire.
The move comes almost a year before a law protecting the rights of older workers is introduced.
A spokesman for the attraction, which includes a safari park, denied the move was anything to do with the law change.
The Seventh Marquess of Bath, 78, handed over the running of the estate to his son Ceawlin, Viscount Weymouth, earlier this year.
A new chief executive officer, David Bradley, was employed to manage the attraction when Lord Bath stepped down.
The Longleat spokesman said employees over the pensionable age had their contracts ended in the last fortnight.
He said that no redundancies had been made.
At present, an employer can compulsorily retire employees at 65 but from October 2011, they will no longer be able to.
The spokesman said: "All the contracts for these people allowed for retirement at 65 and all that has been done is that this has been enacted.
"These contracts - which have lapsed in terms of the over-65 retirement - hadn't been enforced and they are now enforcing this."
He said the retired workers were from all areas of the estate and included 18 workers over 70, seven over the age of 75 and two members of staff in their 80s.
He added: "All staff that were in estate accommodation will keep their accommodation and the estate is ensuring they'll be provided for as well as possible."
A statement later released by the management of the Longleat Estate said retiring the staff had taken "much consideration" and had been a "difficult decision".
It added: "The estate is extremely grateful for the valuable service provided by those employees but as we embark on a sustained multi million pound investment and modernisation programme it is inevitable that we require people with new diverse skills and experience from a variety of backgrounds.
"This is crucial to maintain our position as the premier safari park attraction in Europe and crucial to our dedication to providing an updated, diverse and exciting mix of attractions."
The move was not welcomed by unions.
Trades Union Congress (TUC) regional secretary Nigel Costley said: "We're very concerned that Longleat seem to be one of the first to try to pre-empt the legislation in this way.
"Any company that is discriminating on the grounds of age should be challenged.
"It would appear that Longleat is doing this in advance of the law change, but businesses should learn that a diverse range of employees of all ages gain the benefits of wisdom and knowledge and stand to reflect the customers that they are serving.
"I'm sure that Longleat would want to attract people of all ages and this should be extended to their workforce."
The estate includes Longleat House, where Lord Bath said he would continue to reside after stepping down.