The Whit Walks started in 1800 when the Sunday Schools gathered once a year to parade around town. Over time, the parades became associated with Whit Sunday, the seventh Sunday after Easter. They continued into the 1950s and have recently been resurrected. More information on this page.
I happened upon this year’s Whit Walk entirely by accident when I cycled into town yesterday. I didn’t even catch it all, but it took a good half hour to pass my position. I’ve uploaded pictures to Flickr and you can see all the photos tagged “whit walk” here.