Loch Lomond Brewery has partnering with Nottingham brewery, Castle Rock on a new teacake stout to be launched later this summer primarily in cask with a limited keg release.

Fit to Fly, a 4.1% teacake stout made with cacao nibs in the mash, takes its name from the story of RAF fighter pilots in the 1960s who allegedly had to ban their favourite chocolate covered teacakes from training after a series of cockpit marshmallow explosions.

Last year, the RAF Centre of Aerospace Medicine gave pilots the all-clear to fly with the sweet treats after tests in an altitude chamber found they did not explode in the contemporary cockpits of today.

This latest project follows a successful collaboration between the Glasgow-based brewer – one of Scotland’s most-awarded breweries – and Castle Rock – Nottingham’s longest standing independent brewery – in 2025 to create Pub Tropicana, a 3.8% tropical IPA brewed with Dolcita and Citrus hops.

The new beer will be available through Loch Lomond Brewery and across the 21-strong Castle Rock pub and bar estate across the East Midlands.

“Our brewing teams hit it off straight away when we first met at BeerX in Liverpool a couple of years ago. We share the same values and attitudes towards creating great beer and it worked really well with our Pub Tropicana release last year. We are confident this one will be a real winner and the spirit of fun we share will come through in every pint,” said Euan MacEachern, head brewer and distiller.

Rachel Ghent, marketing officer at Castle Rock Brewery added: “We’ve loved collaborating with Loch Lomond. Pub Tropicana was all about celebrating the Great British pub brings people together, something very close to our hearts as we’ve been running safe and welcoming pubs for coming up to 50 years.

“Fit to Fly is a celebration of tea cakes though, which is really close to our tummies! We’ve had a lot of fun with these beers and I can’t wait for the first pint, which as autumn approaches I expect will be in a warm and cosy pub, perhaps accompanied by a popular brand of chocolate-covered marshmallowy goodness.”