That leisurely stroll through the Peak District is about to get a lot more zig-zaggy, thanks to Pat Tatera's marvellous invention, Pat's Backcountry Beverages.
The 450ml eponymous flask acts as a beer producing sodastream. All you need is a pouch of beer concentrate syrup (a variety of flavours are available), Eco2Activator carbonater powder (a bubble-birthing mix of sodium bicarbonate and citric acid) and 450ml of water. Add all the ingredients, shake, and hey presto it's beer-o'clock.
The Backcountry Beverages uses Tatera's own patented 'Hybrid Brewing Technology', a system that allows him to produce the concentrated beer syrup without having to brew beer and then go about removing the water. The magic mix still contains barley, hops and yeast - it's just much easier to take on a trek than a 12-pack.
You can import Pat's Backcountry Beverages from his website. And be sure you know the route home before you polish off the whole flask.