The initial BBC projections haven't always been right on, but their track record is pretty good overall:
2017 - projected Tories short by 12 (actually short by 8 )
2015 - projected Tories short by 10 (actually a majority of 12)
2010 - projected Tories short by 19 (correct)
2005 - projected a Labour majority of 66 (correct)
2001 - projected a Labour majority of c.160 (actually a majority of 167)
1997 - projected a Labour majority of c.175 (actually a majority of 179)
1992 - projected Tories short by 25 (actually a majority of 21)
1987 - projected a Tory majority of 26 (actually a majority of 102)
1983 - projected a Tory majority of 146 (actually a majority of 144)
(They didn't provide an exact figure in 1997 & 2001, giving just a rough estimate.)
They were rather off in 1987 & 1992, but otherwise were pretty close on all the rest (though you can debate if their 2015 exit poll was 'close' or not, I suppose).
At which hour can we expect this?
