As the UK enjoyed an extra hour in bed over the weekend to signify the end of daylight savings, royal staff have been busy at work in Windsor Castle.

Taking to the Royal Family’s Instagram account, a team of horological conservators worked throughout the castle to tweak the 400 clocks of the estate to set the time back one hour.

Of the 400 timepieces on the state, 250 are located inside the castle.

Offering a glimpse into their many clocks, the Royal Family shared a picture of their chief horologist with the caption, “For those living in the UK, don’t forget that clocks go back an hour tonight.”

“Did you know there are over 1,000 clocks within Her Majesty’s official residences?”

“Each timepiece is conserved by a special horologist and each will be set back an hour this Sunday.”

The estate’s head horological conservator explained that a lot more work is involved to wind the clocks back in the winter than turning them forwards in the summertime.

“We have 400 clocks on the estate of which 250 are inside the castle and the rest are distributed around the estate. I go round once a week to wind them up so I get to know every clock very well”, he said.

“Just like a car that needs an MOT every now and then a clock will need a service every couple of years, twice a year we have the clock change.”

“When we set the clocks backwards in winter it’s a different process for every clock, in summer it’s much easier because every clock just goes forward one hour and each time it takes me about a weekend to set all the clocks to the right time.”

The royal estates features musical, astronomical and miniature clocks including 600 at the Queen’s official London residence Buckingham Palace and 50 at the Palace of Holyroodhouse in Scotland.

Windsor Castle in Berkshire is where Her Majesty is currently recovering after recent stay in hospital.

Image credits: Getty Images / Instagram @theroyalfamily

This article first appeared on Over60.