Hi on interview ratios, LU are known for interviewing quite a lot (400+) for 120 places (they also have another 40 odd coming up from their prep). I was told by a head that LU put more emphasis on 'personality fit' (and consequently the interview) than the other Hammersmith schools. SPGS interview about 200 for just over 100 places. However, at least 20 of those places go to students from Bute and another school (Faulkner) every year. I'm afraid I can't remember the stats for G&L but I imagine the numbers called for interview are somewhere mid-way between LU and SPGS?
I will ask my DD and friends later what they were asked in the interviews. But this was several years ago and they had 2 x 15 min interviews (one teacher each time). Sounds like that has changed.