How do they do this?

can somebody please tell me how meccabingo are serving that landing page? yet the normal homepage is being cached?

can somebody explain exactly how they're doing it please?

google mecca bingo sorry, i can't post links

thanks!

They could be doing something as simple as New IP detection. If you haven't previously been to their website they show you an alternate landing page.

probably through a cookie, cookie is store on your computer, once it expires, or you clear your cookies you should be able to see the landing page again, I have done this with a light box plugin for joomla a while back, it opens up a light box and I had it play a video, I set the cookie to expire every week, once a new visitor came to the site the light box would pop up, if you had been there before you would just be taken to the home page no need to view the video every time you load the page.