A proponent of embryo-destructive stem cell research in Britain tells the truth:

Britain is the first country in the west to authorise by law the use of embryos left over from fertility treatment for such research. Leading US scientists have come to the UK to join what Lord Winston calls "one of the most exciting areas in biology". But, he says, embryonic stem cells may not be useful for a long time.

"I view the current wave of optimism about embryonic stem cells with growing suspicion. Embryonic stem cells replicate very slowly in culture, and it may well be that in the culture systems where you want to grow them the selective pressure is in favour of the faster growing cells, the ones of course which are most likely to be genetically abnormal," he said.