OP, a bit of an aside, but you you might find the following interesting.
Teachers grade predictions are rapidly getting more and more far fetched inaccurate year by year. It's not a good thing as it makes the whole process more crazy and unpredictable than it is all ready and, I imagine, it's only going to get worse as AS's are stopped.
Only a measly 21% of students in England who are predicted ABB or above achieved their predicted grades in 2014. It's stressful and disappointing for students to underachieve and may mean that if the students have firmed a university at the top end of their predicted grades that they end missing their firm offer.
There is more info on page 67 of the UCAS end of year report.
Here is a cut and paste from the report.
For predicted grade profiles of AAA and lower the proportion attaining ABB+ has decreased in every cycle since 2010.
For English 18 year olds predicted ABB, the proportion attaining ABB+ fell from 32.2 per cent in 2010, 29.6 per cent (2011), 25.9 per cent (2012), 23.2 per cent (2013), to 21.0 per cent in 2014. This is a total decrease over the period of 11.2 percentage points meaning that those predicted ABB in 2014 are around 35 per cent less likely to achieve it than those predicted ABB in 2010.
For those predicted AAB, the proportion attaining ABB+ fell from 58.4 per cent in 2010 to 46.0 per cent in 2014, a reduction of 12.4 percentage points (21 per cent proportionally).
The proportion of those predicted AAA and attaining ABB+ has also fallen across the period, from 85.5 per cent in 2010 to 74.6 per cent in 2014, a reduction of 10.9 percentage points (13 per cent proportionally).