Later I got a second reference on pensions funds sustainability,  from wsws.org (world socialist web site, a place where interesting things are found, still I rarely go there, because i think is biased from the start - yet I read often the Financial Times!? ). Follows an excerpt of the article "Britain: Truth suppressed about pensions crisis", by Jean Shaoul (17 March 2004).

The Office of National Statistics (ONS) postponed the launch of Social Trends No. 34 while it reprinted a version that was more to its liking.

Academics Sara Arber and Jay Ginn, from the University of Surrey's Centre for Research on Ageing and Gender, introduced the 2004 edition of Social Trends with an article entitled Ageing and Gender: Diversity and Change.

It made clear that the government's abandonment of one of the central pillars of the welfare state--universal pension provision through the redistribution of income by the state--would have disastrous consequences for the elderly.

Arber and Ginn then exposed the fact that the funds existed to prevent such a situation from occurring. The National Insurance Fund--made up of workers' contributions and used to pay pensions, sick pay, unemployment benefits, etc.--was in fact in surplus.

More recently a honest and concern senior politician, just before leaving my country, called attention discretely to the IMF Working paper WP/05/71 - "Aging - some pleasant fiscal arithmetic" -, from David Hauner.
I could not understand it, though. Can any of you?