The Saga crossword can be found in the monthly magazine Saga, which is published principally for (ahem) older persons. There is no age limit on readers, so I suppose anyone can subscribe to it. You won't find it in a shop, so, if you're interested, have a look at www.saga.co.uk
The prize crossword (you get £100 if your solution is first out of the hat, if not, you get a Bloomsbury English Dictionary (v. nice: I won one)) is fiendishly difficult. Saga doesn't make any concessions to its (ahem) older readers. Overall, it's quite a nice magazine.