THE royals could face their first-ever industrial action as a ballot of ripped-off Windsor Castle staff begins today following the breakdown of pay talks.

The PCS union, which represents 60 per cent of Windsor’s wardens, labelled its members’ situation “scandalous”.

Royal household salaries are now below the living wage, after years of pay restraints and a failure to implement last year’s pay deal.

The 120 PCS members will be deciding on whether to take action short of strike, including withdrawing from all volunteer work.

A union spokesman said: “The household has slipped behind the living wage because it hasn’t implemented the last uplift from November.

“This will mean any new recruits and, particularly, any seasonal staff that are taken on won’t be paid it.”

Wardens are currently paid as little as £14,400 a year for myriad duties, providing castle tours, interpreting and first aid “goodwill” services.

Staff narrowly accepted an offer last year on the promise that additional allowances for such voluntary work would be included in 2015’s negotiations.

But PCS said senior royal household officials have since refused to pay staff for the important extra work.

A Royal Collection Trust spokeswoman denied the claim, saying that wardens were “offered voluntary opportunities.”

These tasks “are not compulsory aspects of their role, and it is the choice of the individual whether they wish to take part,” she added.

“Wardens at Windsor Castle are paid above market median based upon the regional living wage and receive a range of benefits, including a 15 per cent non-contributory pension and a free lunch.”

The trust, which employs the wardens, argued that it continued to award “an annual performance-related pay increase of up to 2.5 per cent” and “one-off payments to those who have reached the top of their pay scale.”

But PCS general secretary Mark Serwotka was unimpressed.

He said: “It is scandalous that staff are so appallingly paid and expected to do work for free that brings in money for the royal family.”

Republic’s Graham Smith said: “It is a failure of leadership on the part of the Queen that despite receiving close to £300 million a year in public subsidy she continues to pay staff so badly.

“It is typical of the royals that they continue to demand more money for themselves, spending millions on refurbishing their homes, yet they exploit the goodwill of those ordinary hard working people that keep the palaces running.

“It’s time the Queen handed over the running of the palaces to the government, so staff have the opportunity to call to account those who are paying them and have a greater chance of demanding a fair, living wage.”

Today’s ballot, which runs until April 14, is not the first time the union has come head-to-head with the monarch — Buckingham Palace cleaners staged a protest during the 2011 royal wedding demanding the London living wage.