What does 'followed Comerford into the referee's notebook' mean?

Answer 1

I means that Comerford was cautioned and shown the yellow card, and the player being described was also cautioned immediately or shortly thereafter. The referee generally has a notebook to keep the official record of goals scored, sanctions issued, and substitutions made. As such, a player who is cautioned and shown the yellow card is often said to have been "booked", or in the case of this question, Comerford was "put into the referee's notebook", followed by the player described.