For those not signed up for notifications from zwiftinsinder, because ZwiftHQ have failed to announce it themselves as far as I can see, there are double XP group rides today and next Tuesday.
They’re every three hours, next one is at 1415 BST (just under 90mins from time of posting), lasting 45mins with late join enabled.
scheduling these on the same day as the most popular racing series is a strange decision 
Awesome, thanks for letting us know Steve, they are a surprise!
There were 540 riders in the one I did this morning. Big group at roughly Coco pace doing 30-31km total in 45 min.
Oh, after no XP Express on Tues 30th, it’s randomly running again today… One just started a few minutes ago at 1215 BST (late join available), Watopia Waistband this time, again 45mins event.
.
And again no announcement by ZwiftHQ ahead of event, from what I can see.
Surely @James_Zwift can be brave enough to simply post an announcement, or get another ZwiftHQ colleague to post an announcement in advance?
Thanks Steve, it looks like there are only two more today, 15:15 BST and 18:15 BST 
Looks like Wednesday 5/8 there are more XP Express events running every few hours that day.
It’s random XP Express day again from the great communication virtual cycling app, today’s offering is RGV, next one at 1215 BST and then every three hours until 0315 BST.
I’m just happy to have an event on that starts between 2000 and 2030 utc. It’s usually a bit of a dead zone. Being double xp is a bonus.