The staff in question do not work for the Queen, nor are they members of the royal household.
They work for Royal Collection Trust.
In a statement, the Royal Collection Trust said:
"Wardens at Windsor Castle are paid above market median based upon the Regional Living Wage and receive a range of benefits, including a 15% non-contributory pension and a free lunch.
"Royal Collection Trust continues to award wardens an annual performance-related pay increase of up to 2.5%, in addition to the cost of living increase (in line with treasury guidelines), as well as one-off payments to those who have reached the top of their pay scale.
"We don't anticipate any interruption to the running of tours for visitors to the Castle."
Buckingham Palace declined to comment.