This chick appears to be the boss chick. There is often one whose development is ahead of the others. It is interesting to see how much the chicks' personality differs from one bird to the next. I don't believe I am getting anthropomorphic to talk about personality. Some chicks are confident and aggressive, some are quieter and others are rather timid. It is the timid chicks who are the last to leave the nest and only appear to go because everyone else has!
These chicks are becoming the bluetit equivalent of teenagers!