If you put something up on the web, you need to give it a date stamp. Not doing so makes you look like Squidoo.
So I’m shocked (no, actually, I am quite surprised!) that parliament.uk thinks it’s acceptable to leave them off. Maybe it means they just don’t care about things like accuracy. I guess it’s easier than simply saying so on their home page. “This is the website of the UK parliament. We don’t care about our content or whether or not you find it helpful.”