Thumpers are out of use now Mrs D. The Lucas Device is a different animal and, as for as I know, designed for adults. Recent research has identified wide variation in
CPR quality. You can probably regulate compression depth and frequency pretty accurately and fit in the required number of effective bag and mask ventilations, without interrupting compression, on a tubed or untubed patient. I've recently confirmed that I can still do it.
But most people who haven't taught it can't achieve these things.
The European/UK Resusctiation Councils and the American Heart Association have been converging their standards for about ten years and I've heard that these standards are due to arrive here any time.
However, they do differentiate between professionals and first aiders to a large extent. For the latter group, I think ventilations are going to become a thing of the past.