SWINDON: Girl guides will celebrate the Big Brownie Birthday at their B-Wise Sleepover on Saturday, April 26 and Sunday 27 at The National Trust HQ. More than 200 Brownies and 39 unit leaders will come together at the event from 9am on Saturday to 10am on Sunday. Fifty-nine Brownies and 15 leaders will also take part in the B-Wise Challenge.