Can't speak to the inbound delay last week, just one of those things I guess.
As to the reporting ready. One of the causes of delay at Heathrow are crews reporting ready when the steps are on, airbridge on, doors open etc. etc. etc. When GMP has to put on a delay and crew's start to hear delays building, often the next crew calls when not quite ready and so on to get to the front of the queue. Soon enough we have 15-20mins delay with only a few actually ready to go. Hope that makes sense.