The normally drab mass of miserable commuters on the London underground was shot with a streak of royal purple.
At almost every station leading from Kensington to Victoria, Paddington, Waterloo and King's Cross, there were people wearing trilbys banded in the bright colour as they made their way home.
Emblazoned on the front was a single word: Tribute.
Each of the people wore them as a badge of honour, having come from this year's Great British Beer Festival.
The ale extravaganza is the largest of its kind in the UK, attracting 55,000 to west London over five days of sipping, supping and quaffing.
What they get is a cornucopia of 800 top-class beers, ales, ciders and perries from across the UK, and some foreign ones as well.
The purple hats were a sign of the Westcountry's presence in force at the event, being dished out by St Austell Brewery, initially to lucky punters free of charge, then later for a donation to charity.
Elsewhere, another of the region's beer staples was turning heads. Betty Stogs, the buxom heroine of Skinner's Brewery in Truro, was giving punters the glad eye, from behind her five o'clock shadow.
With the Falmouth Marine Band in tow in full Cornish tartan, she was marching around the cavernous Victorian exhibition centre, to a variety of emotions from punters.
The event is important for several different reasons.
There is a good deal of networking going on, especially on the first day, which is trade only before the public hordes are admitted.
The majority of the 800 beers on sale are bought from brewers by Camra and each country in the UK is well represented. But brewers can fork out and have their own bar at the event, which means they can stand out from the rest.
St Austell was one of them this year, with a bar featuring a big screen showing a shot of St Ives beach on a glorious summer day.
"It was probably about 2003 the last time we actually had a bar at the Great British Beer Festival," marketing director Jeremy Mitchell said.
"We were going to do it last year – we had won the regional cask beer award [for Tribute] and we wanted to tell the world about it.
"But the event last year clashed with the Olympics so we decided to do it this year instead.
"The goodwill and welcome has been amazing."
He said that the event also gave the brewery a chance to thank its licensees by bringing them up to London for the event.
It also gives them a chance to show off some of the less well-known of their beers on tap.
Alongside Tribute, Trelawny and Proper Job were the ebony 1913 Stout (its first stout since the First World War), Nicholson's Pale Ale, made for the pub chain, and the 9% alcohol behemoth Big Job.
The festival, and others like it, come against a backdrop of difficult times.
The decline in the number of pubs – 26 closing every week – has been well documented.
The Government has backed away from minimum prices, something supported by Camra as a way of allowing publicans to compete against supermarkets.
But it has not been all bad news, with Chancellor George Osborne scrapping the Beer Duty Escalator at the last budget.
The escalator, introduced by Labour in 2008, automatically increased tax on beer at 2% above the rate of inflation.
Among the decline in alcohol sales generally, real ale and craft beers are outperforming the rest of the market, along with cider and perry.
There is also a huge variety of beers on offer as brewers experiment and revive long-lost styles and recipes – dark beers like stout and porter especially becoming more common.
As well as the bigger Westcountry breweries, beers from the best of the smaller ones were on display at the festival.
On the Society of Independent Brewers bar were the Gold winners from its National Beer Competition.
Of the eight beers, three were from the South West: Dartmoor Brewery's Three Hares, Quantock Brewery's Wills Neck and Monkey IPA, by West Dorset's Art Brew.
"It's a huge opportunity for us to talk to other breweries and find out what they are doing," said Tim McCord, director of Princetown-based Dartmoor.
Best known for its Jail Ale, it has seen sales grow 50% in the last year and has spent £250,000 to allow it to deal with increased demand.
He said there had been change in people's attitudes towards ale, with more likely to try a beer "they have never heard of".
But that brings its own challenge, with new microbreweries springing up all the time.
"There are around 1,000 small breweries now and there are 50,000 pubs. So if you do the maths there is one brewery for every 50 pubs," Mr McCord said.
"The challenge for small breweries is to differentiate themselves.
"We have to work very hard in the face of that competition."
As well as the business side of things, there is of course the important business of the competition to find Britain's best beers.
The supreme winner was from Yorkshire – Elland 1872 Porter – but there were also gongs for the region's beers in various categories.
There were silver medals for Gloucestershire brewery Cotswold Spring's Old Sodbury Mild (Mild), Revival, by Somerset's Moor brewery (Bitter) and St Austell's Proper Job (Bottle Beer).
Butcombe Bitter from Somerset (Bitter) and Proper Job (Golden Ales) received bronzes.
Proper Job was also among the ten beers to try at the festival, selected by top beer writer Roger Protz, author of 300 More Beers To Try Before You Die!
Between the big players and the smaller ones, there was certainly a Westcountry feel to the event, things being done bigger and louder.
It will have grabbed people's attention, as the purple hats did on the Tube as people headed home in high spirits.
The result, apart from some very sore heads, will hopefully be more good news for beer.