If my DD was ranked 151 I would be celebrating.
I cannot, in a month of Sundays, think that she wouldn't get in. Our tutor told me that of the top 120, normally only 30 actually take their places and I know of one child last year who was placed around the 230s and still got in. Stop worrying, she'll be fine.
I'm not sure the tutor was quite right on that. It is, I think, usually more than 30 (or 25%) for Stroud. The tutor was probably using the logic that there are 4 schools a child can tick, that every one will tick all 4, that therefore only a quarter of those ticking for Stroud actually want a place there as their 1st choice and given that PAN for SHS is 120, that = 30 pupils...
The dynamics of tick boxes don't quite work like that, especially for the Stroud schools, as there are quite a few people who wouldn't consider Denmark Road, Ribston or Pates on grounds of distance. There are a LOT of girls there who attend from the local towns & villages. My gut feeling says that it's closer to 50% who take up their place.
Of the children below 120, quite a few will also not take up the place, as they've got a place at a more local grammar (or comp).
For Giraffe, though, I'm positive that 151 will get in. Just chill until March (and make sure you put SHS as number 1 choice on the CAF)!