I will admit that I'm not a great admirer of Maguire, but I cannot understand the England fans jeering and booing him at International matches. I don't have any issues giving him the verbals when he is playing in a Manure shirt, as that is just pure banter, but when he is representing your country the fans should be behind the team regardless. On current form, he probably doesn't merit his selection in the team, but that's down to Southgate not Maguire.
As an ROI supporter for a vast number of years, we have had our fair share of donkeys putting on the green shirt, but I cannot remember a single incident when a player was booed or jeered, everyone got behind the team and accepted what was put on the pitch. Yes, afterwards we would criticise and give our opinions on who should have been left in the changing room or that the manager was pure sh*te, but never whilst the game was in progress.
Maybe our expectations were never quite as high as the England team, so we were more tolerant.