Edinburgh’s tram inquiry really sprung into life yesterday when MSP Jeremy Balfour took the stand on its third day.
Up until then there had been plenty to interest those of us who are keen followers of civic affairs - but nothing you could describe as explosive. One former council leader admitting she was effectively fobbed off when she tried to get information, another accusing officials at trams firm TIE of deliberately misleading councillors.
What Mr Balfour - who was a senior councillor at the time - has said is different. His evidence cuts to the heart of one of the main arguments being played out in front of Lord Hardie.
The suggestion that officials, at TIE and within the council, withheld information from politicians as the project started to spiral to disaster is hardly new.
The first witnesses, all politicians, have effectively been putting the case for the prosecution on this point. Next week the officials will have their turn.
But what Mr Balfour has said is that one of the council’s most senior officials shared the politicians concerns, and raised them - only to be told to ‘shut up’. By whom? We don’t yet know. Lord Hardie, however, knows who to ask.