Homepage, down the bottom, link titled "Under the hood" ... et voila: Here's all the details of what we run on.
Note the tech team do not have helldesk duties, because we're nice to them like that. It's effectively BYOD here except the company owns the wide-ranging mix of devices.
(Someone who shall remain nameless because he's no longer here got all clever and installed Tails on his issue laptop, boasting how smart and security conscious he was. This lasted until the point where he had to email me documents he wanted to print because Tails wouldn't let his machine talk to the office printer, despite much wailing and gnashing of teeth)