If Julian Fellowes was set to music he’d be Gustav Holst’s Jupiter, the bringer of jollity. “I like everyone to be happy,” he says. “I love happy things, I never want to be unkind.” I have never heard him say a common or mean thing about anyone. Like Denry in Arnold Bennett’s comic novel The Card, Fellowes is “the great cause of cheering us all up.”

So far Fellowes has cheered us with Gosford Park, for which he won the Oscar for best original screenplay; two novels, Snobs and Past Imperfect; films; television performances; and, of course, Downton Abbey. The series finished in 2015. Cue abandonment issues from an estimated global audience of 120 million.

So now we have the much-anticipated Downton Abbey, the movie, and are re-united with the Crawley family and their servants in 1927, all overexcited because King George V and Queen Mary have invited themselves to stay at the castle. The story is enchanting, like eating an entire box of chocolates at once. With a glass of pink champagne.

Lunching with me at the Ritz—he had the lobster—Fellowes, aged 70, is decidedly a polished man-about-town, but now of many towns: London, New York, and Los Angeles. I have known Julian, now Lord Fellowes of West Stafford, for 50 years. We met when I was a debutante and he a young man new to town. He claims he was only asked “to what was left of the ballrooms of London” because he was an extra chap. Not true. He was the greatest fun to sit next to at dinner (certainly not true of most callow youths) and has immaculate manners. The sort of manners not trotted out by rote but stemming from innate kindness.

The story is enchanting, like eating an entire box of chocolates at once.

He once took me to a dance at the posh Hurlingham Club despite the fact that I’d had a car accident and my mother told him my face looked like a slapped bottom. When he wrote to Lady Camilla Osborne, daughter of the Duke of Leeds, to inquire about some family history, he said, “I know these things are such a bore,” and thoughtfully enclosed a stamped addressed envelope. He mentored Carey Mulligan without fanfare when she contacted him as a schoolgirl.

What I admire about Julian Fellowes is that he seized his 15 minutes of fame when he won his Academy Award in 2002 and has extended it 17 years. And counting. “I have been very lucky. My life changed with the making of Gosford Park.” We were both staying at the Four Seasons Beverly Hills that Oscar night and I remember his greatest concern was adjusting the train of his wife Emma’s gown. A great-great-niece of Lord Kitchener of Khartoum, Emma was probably the only woman wearing her own jewelry.

“My life changed with the making of Gosford Park.

We are lucky, too. The characters in Downton Abbey need no introduction; they were part of our Sunday-night lives for six blissful years. There is the familiar music and the grand house, a character in itself. In these uncertain times familiarity is a comfort blanket. Lady Mary (Michelle Dockery) is happily married to her race-car driver (Matthew Goode); Lady Edith (Laura Carmichael) is now a marchioness and actually smiling, whereas she dripped through the television episodes like a wet weekend (“What is a weekend?”); and Violet, Countess of Grantham (Maggie Smith), is in sparkling form. When asked if she suffered during the General Strike of 1926, she replies, “Well, my maid was rather curt with me.” Best of all, Carson the butler (Jim Carter) is winkled out of retirement to mastermind the royal visit. The production values include a village parade for the monarchs in which the real cavalrymen of the King’s Troop, Royal Horse Artillery, are for the first time deployed as extras as a yeomanry regiment. It required building stables and a camp for 100 soldiers and horses.

Fellowes works like a demon in a charming building separate from his own Gosford Park, Stafford House in Dorset. Mary Poppins, the stage musical for which he wrote the book, is returning to the West End next month, and he is the creator, writer, and executive producer of the forthcoming The Gilded Age for HBO. The 19th-century new rich fascinate him. “They redesigned being rich, they bought yachts and built palaces in Newport for fun, whereas the English with any money would have bought 5,000 acres and had to look after Nanny.”

He is meticulous about English tradition and period detail, but says, “The Americans have a sense of today, of the present, they move forward with fizz and are not, like the English upper class, obsessed with how Grandma folded her napkins. The Gilded Age has the values of modern America.”

In between house-training two puppies and attending the House of Lords, Julian Fellowes intends to keep on writing. “I’d like to keep the show on the road.” Which is cheering for us all.

Victoria Mather is a writer based in London