Royal workers at Windsor Castle are taking industrial action against the Queen for the first time in history over low pay and allowances.
Castle wardens can start on £14,400 ($21,000) per year, lower than the living wage, and are expected to carry out extra duties such as giving tours of the castle for no additional pay despite visitors paying extra for this.
In a ballot of 76 wardens, 84% voted for non-strike industrial action to include the "withdrawal of this goodwill", which has been described as having a "significant impact on the services provided to visitors".
They will not be conducting tours within the castle during August and September and will not be using their language and first-aid skills.
Mark Serwotka, the general secretary of the Public and Commercial Services Union (PCS), which represents 120 out of 200 castle staff, said the "loyal" workers were the "public face of Windsor Castle".
"With this vote their message to their employer is loud and clear," he said. "Staff should be properly rewarded for their commitment to ensuring visitors from around the world can fully enjoy their time at the castle."
The uniform wardens, who are employees of the Royal Collection Trust, and are not part of the Royal Household that include butlers and footmen, work inside the palace and around the grounds, helping the public and protecting the exhibits.
The PCS said it only "narrowly accepted the unsatisfactory pay offer" on behalf of its members last year based "on the understanding that additional allowances for paid-for tours and other skills would be considered this year".
Serwotka previously told the Daily Telegraph: "It is scandalous that staff are so appallingly paid and expected to do work for free that brings in money for the royal family."
A Royal Collection Trust spokesman told IBTimes UK: "Following the union ballot, we have been informed that some PCS-affiliated wardens at Windsor Castle will no longer participate in various activities undertaken during their working day, including using their language and first-aid skills, and conducting tours of specific areas of the castle during August and September.
"These activities have never been compulsory; it has always been the choice of the individual as to whether they take part. While the outcome of the ballot is disappointing, it will have no effect on services to visitors to the castle.
"Royal Collection Trust has since last year been exploring ways to achieve an agreed level of pay for all warden staff. Conversations that are part of the annual pay review process are still ongoing and an offer to expand the salary scale for a warden, starting at the Regional Living Wage of £14,695 for new joiners (based upon an average 36 hour working week), has been put to PCS and other unions."
Windsor Castle, which attracts 1.1 million visitors each year, is used by the Queen as a weekend home and often used in banquets and official entertaining. More than 500 people live and work in the castle each year.