There was much excitement when Jennifer Saunders, David Walliams and Timothy Spall began filming their new BBC comedy, 'Blandings', at the castle earlier this year.
The famous trio were joined at Lord and Lady Erne's house outside Newtownbutler by Harry Potter actor Mark Williams and singer Paloma Faith who also star in the six-part series.
"It all started back in January and at that stage we didn't realise how big it was going to become," said Mr Johnston, manager of Crom Castle.
"The preparation commenced in January, in February the team started to arrive and then in March they started filming. We were very proud and honoured to have all the celebrities with us, including David Walliams who we have become great friends with since," he said.
'Blandings', a comedic period-drama set in 'Blandings Castle' in 1929, is adapted from the novels of acclaimed author P.G. Wodehouse and will air on BBC One in the New Year.
Mr Johnston joked that Crom looked a lot like "Heathrow Terminal" first thing in the morning, with stars and crew coming and going during the period of filming.
He also said he found it amusing to note that the sound of birds chirping in the castle grounds stopped the crew from filming, which was a little different to the noise of aeroplanes, trains, and traffic which usually hold them back in England.
"Having them here was not only good for us but for Fermanagh. Each and every one of the stars fell in love with the county and the surroundings and that can only be a good thing for the area.
"I found them all really down-to-earth and at the end of the day, they just wanted what we all want after a long day at work -- a bit of comfort," he said.
Then in June, following her historic visit to Enniskillen, Her Majesty The Queen and the Duke of Edinburgh made a private visit to Crom for lunch with Lord and Lady Erne.
"It was astonishing to have The Queen and the Duke with us; it was actually one of the biggest things that my wife, my mother, the children and my family have experienced. It was historical.
"Growing up and hearing about the Royals all my life and then to meet the Queen in person in my own back garden was amazing; it will be something that my wife Amanda and I will never forget, particularly as we celebrated our 25th wedding anniversary on the same day," he said.