I first met Peter Plesch in the late 1950s when he had established his vacuum techniques in Keele and I was embarking on my PhD. My visit to Keele was to seek advice (freely given) on handling sensitive reaction systems. I rapidly came to appreciate that Peter operated on a somewhat higher intellectual plane than many academics. All might claim a common goal in achieving an understanding of how reactions or other processes work. But, while some are happy with an easy, sensible-sounding explanation, Peter took no easy line and needed to know how things really worked.

Throughout his scientific career, Peter worked on cationic and related polymerisation processes for which he coined the collective term cationoid polymerisations. Compared to free-radical or living anionic polymerisations, in the earlier days cationoid polymerisations were theoretically and experimentally difficult and constituted a Cinderella field limited to a few aficionados; most of us positively avoided the subject. A feature of meetings of the High Polymer Research Group in the 1960s and 70s, held in a room with a small balcony at the Manor House Hotel in Mortonhampstead, was that Plesch and Pepper, two of those aficionados, inhabited the balcony. When relevant, they contributed enthusiastically to discussions (often disagreeing with each other) and their mutual discussion on detailed and probably obscure mechanistic features descended as ‘from on high’.

Solving the detailed reaction mechanisms to produce rational explanations of cationoid polymerisations and reliable values of kinetic parameters has been Peter’s consistent goal for over 50 years. Unlike many people who devote their lives to a single topic, if, in order to advance the subject, some new experimental technique was required he and his group developed it; over the years they developed several devices and procedures to generate more-reliable data. Peter, therefore, was a serious experimentalist as well as a careful analyser and scrutinizer of data, data of his and of others. Over the years he freely criticised not only the work of others but also his own work (as is apparent in this volume) in order to develop a more complete understanding of systems. Thus, this book reports his contributions ‘warts and all’ where one paper may criticise a preceding paper.