I hadn't seen this posted - pls delete if necessary.
The blurb at
http://www.ichotelsgroup.com/h/d/ex/...anner&a=b.html says:
'...
when you register and stay twice at any participating Express by Holiday InnŽ, or sister brand by 30th April 2009 you can claim a free night to enjoy at your leisure at one of over 4,100 hotels worldwide.
Your free night will be available to take any time after 15th June 2009.'
Of course, that's not the offer at all.

It's a repeat of the offer where any points you earn in the qualifying period are topped up to 25,000. And if you earn 25,000 or more, you get zilch, as outlined in the worked examples shown in the link. Good that they show the examples - should reduce the number of non-qualifying retroclaims.