I came to play the role of Mr Pritchard by a curious turn of events.
And the part kind of landed in my lap from that really.
It was totally unexpected and extremely flattering. I read the scripts and just fell in love with Mr Pritchard and I completely bought the whole idea of 165 Eaton Place being re-imagined.
So rather suddenly, but delightedly I was in Upstairs Downstairs.
I think being a downstairs character suits me as a person - I'm not good with airs and graces.
But the great thing about Mr Pritchard is that he spans both worlds - and very efficiently at that. It's called 'having your cake and eating it'.
One minute he can be opening the front door for Wallis Simpson and the next minute arranging flowers in a vase.
I love the frantic nature of downstairs where we are constantly on the go - preparing food, cleaning clothing - contrasted with the smoothness of upstairs, which has to look utterly effortless and calm.
Being in both worlds also means I get to spend time with everyone in the cast, which is a real treat.
The new version differs from the original as the characters (with the exception of Rose Buck) are all new to Eaton Place.
Heidi has used genuine historical events around 1936 to colour and chart the storylines.
Because of the way the original series had to be made, the camera shots were dictated by the settings. With the new series, a single camera crew made it possible to shoot the scenes any way the director wanted.
The detail of the sets and costumes are astonishing.
By the time I'd put my tail coat, wing collar, bow tie and watch chain on and walked onto the magnificent hall and stairs set, or the low-ceilinged warm and chintzy downstairs set, no acting was required - it all felt so real and convincing.
I have enormous admiration for what the art, costume and make-up departments all created. It was the perfect playground.
My favourite room was the kitchen pantry. There were shelves and shelves of provisions, boxes and jars from the period along with home-made preserves and chutneys, bottled beetroot and pickled onions.
You only catch little glimpses of it in the show, but the art and props departments worked tirelessly to make it historically accurate as well as beautifully evocative.
I've admired her work for years. Let's face it, she's a national institution.
We hit it off the minute we met. She is something of a minx on set. She can make me laugh simply by raising an eyebrow.
Her anecdotes are comedy gold, and she's never afraid to take a difficult path in a scene.
We travelled back from Cardiff (where we shot the series) on the same train a couple of times. My sides ached from laughing by the time we reached Paddington.
She's also partial to a glass of red wine, like my good self, especially on trains, which endears her to me even more.
Eileen's character, Maud, has a pet monkey, which was remarkably professional on set.
There was one occasion however when I was serving coffee by the breakfast table and it wouldn't do what was required.
If I poured the coffee once I must have poured it a thousand times. Every time we went for another take we had to reset the cups, the milk, the coffee, the spills I'd made, the sugar tongs etc. By the end of the scene I wanted to swear at it.
Subsequently watching the scene, you can't really see me doing anything. The monkey steals it every time it's on screen.
I have had a terrific time working on Upstairs Downstairs. Not least because of Cardiff. I know the city pretty well because we filmed Gavin and Stacey there.
I love the shopping arcades and the warmth of the people. I'm desperate to see a rugby match at the Millennium Stadium though. Maybe next time around!
It's going to feel very strange not being around when the series starts.
I'm going on a road trip in the USA with my wife and kids, so I shall have to wait until I'm back to gauge the response and to see what my children think.
I'm always conscious that I have a lot of potential to embarrass them.
Gavin and Stacey gave me a cool quota mostly - I'm not certain of Mr Pritchard's cool leanings. Still, if my mum and her friends like it, that's all that matters.
Adrian Scarborough plays Mr Pritchard in Upstairs Downstairs.
For further programme times, please visit the upcoming episodes page.
Comments made by writers on the TV blog are their own opinions and not necessarily those of the BBC.