Andy Flower, the former Zimbabwean cricketer and current England coach, is apparently unhappy with the Umpire Decision Review System (UDRS).

Flower is believed to not be overly excited about the review system in place for two reasons. Firstly, he believes the system is demeaning to the umpire on the field by questioning his authority and secondly, it is a time wasting scenario which Test cricket can avoid.
Everyone seems to have an opinion on the system and it remains to be seen if it can undergo the trial and error process before it passes the test.
England are currently touring South Africa where the system has been, on a mandatory basis, been applied.
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