As we pulled up to the front steps, Alex - otherwise known as the Earl of Mount Charles and son of the owner Lord Henry, Eighth Marquess Conyngham - emerged.
Casually but smartly dressed, he usherd us inside to shield us from the rain.
It took me a few minutes to adjust to the chilly air in the main hall - roughly the size of four generous lounge rooms - and soak in the enormity of the sparsely-furnished space.
It's fair to say I was in unfamiliar territory.
Never before had I been to an Irish castle, let alone met an earl for a personal tour of a house steeped in such history. It was a far cry from my life in suburban Sydney.
The property, located about 45 kilometres northwest of Dublin in County Meath, has been owned by the Conynghams since 1701, Alex explains as he guides us toward the castle's west wing and into the pink drawing room.
The family bought the estate from the King of England, who'd confiscated it during the infamous Battle of Boyne fought just a few kilometres upstream.
Our host points to the river through the window and, beyond that, the Hill of Slane, where St Patrick is believed to have lit the paschal fire while converting Ireland to Christianity.
Ironically, the room in which we were standing had been all but destroyed by a fire in 1991 - along with a third of the castle's rooms. It took a decade to restore the building but some visible burn marks remain on the wooden floor in the doorway of library next door.
It's there Alex reveals to us some of the more saucy details of his family's past.
His great-great-great-great-great-grandmother - Elizabeth, the first Marchioness Conyngham - was in fact King George IV of England's final mistress and Slane often provided the setting for their historical romance.
The king was said to have regularly dined in the Gothic Revival ballroom and slept in what is still known as the King's Room.
But the family's link to fame and fortune didn't end there.
Since 1981 the house and its sloping grounds have played host to Slane Concert, a music festival involving some of the world's biggest stars - from U2, David Bowie and The Rolling Stones, to Guns N' Roses, Madonna and the Red Hot Chili Peppers.
It was the brainchild of Alex's father Lord Henry, who we conveniently bump into on our way back through the main hall.
Donning a black "Slane Rocks" T-shirt, it took no time for the well-known eighth marquess to share his excitement about the event, which has regularly drawn crowds upwards of 80,000. Kings of Leon headlined the most recent show in 2011, although none are scheduled for this year.
It certainly put Slane on the map and armed Lord Henry with a stockpile of stories about the celebrities he's entertained.
But with the rising cost of hosting the concert, the Conynghams have been forced to look elsewhere to support the day-to-day running of the castle: Irish whiskey.
In 2009 they launched their own boutique blend at an Oasis concert, which proved enormously popular both locally and abroad - particularly in the US.
With just four distilleries remaining in Ireland, the family decided to heavily invest in the new venture and announced plans to turn part of the castle into a distillery and visitors' centre (set for completion in 2014).
As Lord Henry scurries off after our brief meet-and-greet, Alex takes us into the nearby study for the final part of our tour: a comparative whiskey tasting.
The castle began hosting the tutorials as a way of introducing visitors to their blend and a range of other Irish whiskeys - including single malt, single grain, and roasted blends.
Although I'm not a regular whiskey drinker, the class is quite enjoyable and informative.
Unlike wine tastings, it is okay (well, in my view, it's a must) to swallow the sample to fully appreciate the different flavours. The serves are only small but a meal before your visit might be worthwhile for those prone to getting tipsy quickly.
After a few sneaky shots I was well warmed-up and ready to face the cold when we stepped back through the same double doors we'd entered.
By that time the sun had managed to find its way through the clouds, giving me the perfect chance to step back and admire the castle, up close and personal and fog-free.
A fitting end to my visit to Slane.
IF YOU GO
Where to stay: Tankardstown is a wonderfully restored 18th Century estate, less than 5km from Slane Castle. It boasts 18 double bedrooms (six in the manor house and the rest in converted courtyard cottage suites) on 32 hectares of lush countryside.
For the budget-conscious, Slane Farm Hostel offers dorm accommodation, private rooms and self-catering units.
What to do: Slane Castle is in the village of Slane, County Meath, less than an hour's drive from Dublin's city centre or 25 minutes from Dublin Airport. The castle offers one-hour private tours and whiskey tastings with a member of the Conyngham family (subject to availability, minimum 12 people). It's also open for guided tours during select months of the year.
Further information: See discoverireland.com.
The writer was a guest of Tourism Ireland and Etihad Airways.
- AAP
