To send my eldest to grammar school knowing it’ll be a squeeze?

I was raised by a single parent and my siblings and I all passed the 11+

We didn’t get to go to the grammar school and not only that went to a bit of a sink school
We all feel that was a huge missed opportunity. We also understand that each of us were treated differently depending on the circumstances at the time, we don’t begrudge each other those differences

As part of your decision making, I think you should bear in mind that bursary funding is linked to household income. So if your income goes up, your bursary will reduce and you'll be no better off.

Send her, and apply for a job teaching there.
Staff kids usually go free.

I think I would send her.

I don't think you have done anything wrong with letting your DD sit the exam its a good thing so you are both aware of her potential. However she obviously is clever and something will come her way sometimes it's just pure luck.

I personally would not send her though and I know it's a real shame but the reality is OP you are a single parent with 3 kids. It's no life having to penny pinch it's a luxury within itself to be able to just unwind for an hour and have the cake and coffee out to yourself. It's important as a single parent to do these things like this for the sake of your own sanity.

Could you go through CMS to get finical support for your DDs father?

Firstly congractulations. Sorry but if there is around 150 applications and take 60 children it is not so selective school. My DD had offer from one of the independent school this year, applicants were more then 450 and they took 38 children only.
If it will effect my lifestyle other kids clubs, tutors, holidays I woudnt accept the offer. Buti f she get scholorship and bursary I would send her it means she deserve to be there. But I must say the other children may not be able to get that kind of scholorship or bursary and they may ask to go to independent school in secondary as well. It tricky...
Good luck, wish you all the best.

@Musmerian

So what? Lots of children are "clearly very bright".

And the school is obviously not very selective if it takes half the applicants. There are schools oversubscribed by thousands.

@GraciousPiglet

Plenty of grammar schools are fee paying.

I would absolutely send her and try to make ends meet. What a fantastic opportunity for her.

I am one of 3; my younger sibling was the only one to get a private education. No issue at all, my other sibling and I were very happy at our state school.

There are many unwritten extras that accompany private school fees, the expectation to engage in costly out of school activities, join ski trips, city breaks and so on

That's what bursaries are for. At one of my relative's independent school, the aim for this year is to raise a million for bursaries. This will not only cover fees, but can be used to fund trips etc for parents who can't afford them.
This is a top, very academic independent school.

@Blossomtoes OP specifically mentioned her DD being eccentric and being concerned about her fitting in.

@Troisfoisfilles you are already scrimping now. That old car will need to be replaced at some point maybe more than once.

I would do it in a heartbeat. You know that your DD will thrive and the 'sacrifices' are ones that your smaller kids won't notice at the moment.

It's that old chestnut of equal not always meaning equitable.

I'd say yabu if you don't let her go. She sounds like she will thrive there and she deserves that chance.

Although my story is different, it may also help. My parents didn't let me sit the equivalent of the 11+ where I grew up (ideological reasons, although I doubt they could have afforded it either - left wing academic parents) and sent me to a local "very highly rated" comprehensive (although they picked - I was not consulted). I was absolutely miserable there, unbelieveably lonely and picked on for getting top grades - the school, for the first time, had a "girls" and "boys" science prize, because otherwise that would have meant a girl getting the top prize - which I think was their attempt to head off some of the bullying. We had ridiculous situations like me getting 100% in maths tests and the next top mark was 60%.

The only thing in my favour was that I was technically too young for the year - and age wise, fell within the age criteria (just) for the following year's 11+. So I pursuaded my parents to let me sit the scholarship exams (because it was based on age, not year), for an academic private school - we phoned around the schools to check that if I won the scholarship, they would let me go into Year 8, not Year 7, and while most said no, one said yes, I sat the scholarship, won it, and on the basis that I had "earned" my way into the school, my parents let me go. Undoubtedly the best thing that happened to me ever. I don't think I would ever have forgiven them if they had insisted on my staying for another 6 years of purgatory in the school in which they enrolled me.

BTW, after my experience, my parents let my DB sit the scholarship exams for the equivalent boys private schools. My DB won the scholarship - and decided to turn it down in favour of a new state grammar that they were just setting up (it was not selective in my time, three years later, it was). You never know what siblings will or won't want (or what opportunities might be available to them that were not available to the older ones). But there was no question that if he hadn't won the scholarship, they would have sent him to the private school anyway, just because I had. In their view - it was like I had financially contributed the amount of the scholarship (which in those days was full, and not means tested). In a way, it was not their money to throw away, it was effectively money I earned. Just as I would not take my adult child's earnings to subsidise my younger children, it would not have been right to take away what I earned just because my DB might or might not earn the same.

I think, given how much her heart is set on it, you really must let her go.

Really bright kids who get sent to state school are usually just left to rot while the teachers concentrate on the ‘slower’ students. 1,000% go for it! As you said, you’ve got years to figure things out financially before the younger two are secondary age.

I think that’s a brilliant deal OP re the bursary amount. I would absolutely go for it.

Even my school which was a private convent had entrance exams (easy though they just wanted the money!).

OP bursaries are offered on merit/financial circumstances. Having a sibling already at the school in a bursary-aided place strengthens not weakens a younger sibling's application, subject to them meeting the academic threshold. Your contribution is reduced if you have more than one child at a school ( same as with fee aping parents). Part of the schools rationale is that they "know what they're getting" with a sibling in terms of the individual's likely levels of motivation and parental support. The extra curricular opportunities are also astonishing and they don't cost you anything, ditto the range and potential combination of subjects at GSCE and A-level.