It's one of the finest gardens you've never seen – but is something of a hidden gem.
Hillsborough Castle has been the haunt of visiting royalty from all over the world as well as a long line of Secretaries of State, yet most of us don't realise the grounds are open to the public every summer.
That should change after 20,000 visitors descend on the private gardens for the Airtricity Garden Festival this May, but the Belfast Telegraph has explored this secret garden for a sneak preview of what they will get to see.
Snakeshead fritillaries can be glimpsed in the grass, but the bluebells have yet to make their appearance although the signs are that they will be in their full glory when the festival opens on May 17. Daffodils and wood anemones glint along the length of the mossy Lime Tree Walk leading up to the Doric temple overlooking Lady Alice's Pond.
Head gardener Stephen Martelli (below) revealed that the Yew Tree Walk that approaches the pond from the direction of the house was once the main road to Moira when the house was first built in 1797.
Several generations later, the Third Marquess decided to enclose the estate and a new road was built outside the walls.
The bench outside that temple overlooking Lady Alice's Pond was one of the favourite contemplative spots of Mo Mowlam, he explained. The former Secretary of State also had a soft spot for the rushing waterways and mossy grottoes of the nearby Crooked Glen and asked for her ashes to be scattered there.
Over the centuries, each custodian has put their own stamp on the spectacular private gardens.
Lady Granville, wife of former governor Earl Granville, was an aunt of the present Queen and was one of those who poured her efforts into the gardens, designing and planting the Granville Garden to the south of the Castle.
In the coming weeks, this garden will have a particularly spectacular backdrop as the biggest rhododendron shrub in Europe bursts into full bloom.
During the darkest years of the Troubles, much of the castle's garden fell into disuse as successive Secretaries of State focused their minds on more pressing matters.
Now the gardening team have made use of the wet winter days when they were unable to carry out their usual work to clear back the undergrowth.
"We have researched through old Ordnance Survey maps and found the paths and driveways that had fallen into disuse," Mr Martelli said.
"Little by little, as resources allowed, we used our time on wet days to go back and open up the paths as they used to be."
On one of the newest paths to be cleared, a carpet of bluebells has sprung and should be bursting into bloom for the festival.
Five things you didn't know about Hillsborough Castle gardens:
1 Hillsborough Castle is self-sufficient in eggs which are laid by its own flock of hens in the pinetum. There were originally a dozen but two were lost to a buzzard.
2 A Quaker burial ground lies within the property, dating back to the days before the 3rd Marquess of Downshire enclosed the land and built a new Quaker meeting house in the village.
Once a year Quakers gather in respect for the dead.
3 The walled garden is also known as the Secret Garden after it was given the name by Mo Mowlam's stepchildren. She decided to have the overgrown garden cleared and restored after they came back from playing there and told her about it. Many of the espalier fruit trees growing there now are the originals that had been concealed in undergrowth.
4 Three examples of wollemi pine have been planted in the gardens – a tree that was thought to have become extinct before it was found in an Australian gorge and propagated. One of these was planted by Prince Charles.
5 The gardens are home to kingfishers, wildfowl, badgers and foxes.
One night staff witnessed a fight between a fox and a badger over a wasps' nest. There was also a recent fight between a fox and a swan – the swan won.