Well, I can't speak to the boys results as I have daughter, but I can say my daughter loves attending Falkner House Nursery. She loves going to nursery so much that on weekends, during half-term, holidays etc. she often asks if she can please go back to school. She's sometimes gotten very sulky or "fake cries" when we say no, because it's the weekend, but you can go back on Monday. Both my husband and I have also tried asking about her teachers, and she only has good things to say about them. While we were reading the book "Starting School", I attempted to ask if sometimes her teachers get grumpy too or are not cheerful (like in the book), and she said "No, my teachers are always nice." I kept trying to ask in different subtle ways, but she shot me down and finally asked if we could "please continue the book". Fair enough.
She only just started last September, but in less than 1 year, her language, math, social skills, and phonics have accelerated. We don't do any tutoring or reinforce that much more at home beyond the normal (e.g. reading bedtime stories regularly, weaving counting games in here and there), so I'd have to attribute at least 80% of this progress to the nursery. And to her, it's all fun and games. She's always so proud to show us her little book of projects at the end of term.
Note that the staff turnover is basically non-existent, which says something about how the school treats its staff (unlike some other well-known nurseries around West London which clearly have a profit-driven agenda due to corporate / private investor ownership structure). FH teachers are happy, they like their jobs, and that atmosphere clearly translates to the children. You can very much tell it's a school with a family run vibe.
I will say out of her class of... 20ish boys and girls, there are like 1 or 2 who have taken a while longer to settle or are maybe not settling in quite as well (the boys seem to all have settled in well though). However, I think this has less to do with the nursery staff, and more to do with either the kids themselves (e.g. just by nature, a very shy person) or perhaps their home environment (e.g. lots of change and no consistency at home, parents traveling all the time, a stressful atmosphere for anyone let alone a toddler going through emotional development). There are plenty of reasonable parents, but there's always one or two high maintenance / controlling ones who want things done their way or else. A parent once very rudely told off a nursery teacher in front of me because the school called the parent in to pick up their kid early the day before (as the teachers thought the child seemed unwell and would benefit from rest). I can't begin to describe how unprofessional this parent's behaviour was.... I've also seen parents ask the most ludicrous things because their child is a special snowflake that needs different treatment from everyone else (e.g. can the teachers learn a few phrases in language X so their kid can be understood? as if there are no other bilingual or trilingual kids in the class. Come on, this is London...). Note that the nursery will make individual adjustments for things of actual importance like medical issues.
Some parents think because they are paying X amount of money, the teachers are their servants and should do whatever the parent wants. If that's your attitude as a parent, then definitely give FH a miss, they won't tolerate that. But if as a parent, you view the school as a partner and you are aligned with their philosophy of how to raise and teach kids, then this is definitely a great school for you and your child.