Wood's Brewery, based in Craven Arms, had planned to mark the milestone in April last year, but the celebrations had to be cancelled due to the coronavirus lockdown.
But following the easing of restrictions, and the reopening of food and beer festivals, the brewery decided to mark the occasion by taking part in four events over a five-week festival.
It is using the occasion to promote a new line of craft ales, a special edition gin, and has also re-introduced its first-ever beer.
This weekend the brewery will be exhibiting its wares at the Malvern Autumn Show, and on October 2 Wood's will be offering a two-for-one offer to Star readers at the Shrewsbury Oktoberfest in the town's Quarry Park.
Earlier this month Wood's took part in the Ludlow and Shrewsbury food festivals.
Managing director Stephen O'Neill said: "2020 was the 40th anniversary and we had planned to celebrate in style with a number of limited edition brews and also some commemorative events. "The 40th was in April 2020 and of course this was right at the start of the first lockdown, so all plans were put on hold.
"One of the activities that we had planned was to re-introduce the Wrekin Barrel Race.
"This was a race which was run between 1999 and 2013 and involved both individuals and teams carrying empty and full casks to the top of The Wrekin. This obviously had to be cancelled due to Covid."
He said the past 18 months had been very hard for the business.
"About 85 per cent of our sales are to pubs, so this business was completely wiped out during lockdown," said Mr O'Neill.
"We did improve our bottle sales, but nowhere near enough to compensate and we were forced to make cutbacks in a number of areas in order to survive."
He said as part of the celebrations, Wood's – best known for its Shropshire Lad bitter – had released two new drinks, and re-introduced an old one.
Mr O'Neill said the brewery had teamed up with Shropshire Distillery in Ellesmere to produce a limited edition hopped dry gin, using the Cascade hops which make the Take 5 IPA and Shropshire Lass beers.
"This has resulted in a delicious citrus gin which has been very well received," he said.
"So well in fact that the entire run sold out in 10 days. We have had had multiple requests for the gin from disappointed people so think we need to distil it again pretty quick and the limited edition may not end up being so limited.
Mr O'Neill added that towards the end of 2019 the brewery launched a craft range under the Ironbridge brand, produced at the existing Wood brewery in Wistanstow.
He said the plan had been to expand this last year by finding a brewing location in Ironbridge, potentially in partnership with a local pub.
"One of our craft beers – Ironbridge Coracle IPA – won gold at the National Society for Independent Brewers awards in Liverpool," said Mr O'Neill.
"We had hoped to use this accolade to promote the beer. We won the award on March 12 and pubs were forced to close on March 20 so a bit of momentum was lost."
The brewery will also be re-introducing Wood's Special Bitter, the first beer that the brewery produced in 1980, using the original recipe of hops from Kent and Germany to create a classic English-style bitter.
"We had actually brewed this last year for the spring festivals which never went ahead, so ended up bottling it and that sold old fast. It is now available in cask form both at the festivals and in our two pubs."
The brewery was founded in 1980, at the start of the renaissance in cask ale, following the formation of the Campaign for Real Ale in 1971.