To go to London for the state funeral?

[Tiggythetiger]

DD (16 years old) has asked if we can travel
down to London as she wants to pay her
respects. Obviously she knows she would be part
of a crowd so to speak and not inside the funeral
itself. DH is saying "it's not safe" due to the
amount of people who would be there. Obviously
I would be with DD, it wouldn't be her there alone

I wouldn't personally.

If you arrive on the day, you won't get anywhere near the front, and you won't see a thing, apart from the backs of heads and arms holding up iphones. People will be setting up camp DAYS beforehand. The front row spots will be gone by Sunday morning easily.
I can understand wanting to be part of history, and all that. But I suspect all she'll really remember in years to come is feeling cramped, sore feet, hungry and thirsty, and hours of boredom.

If she physically wants to "do a thing", take her to lay a bunch of flowers at a local war memorial or something.

I think kids and teens get a bit swept up in the drama and public out-pourings, and it's a way for them to explore grief in a safe "not my family" way. I remember it being the same when Princess Di died. I was 13 at the time and DESPERATE to go to the local remembrance service. Never met the woman, hadn't given a single shit about her when she was alive, but suddenly it MATTERED that I was there.