Applying for first UK passport - form question

I am now officially a Brit! I'm very excited, but the process of applying for a UK passport seems almost more difficult than applying for citizenship itself. 

The form asks for details of all of my old passports (including any old US ones) - my problem is that when I was younger and more careless, I lost/had stolen two US passports, neither of which I have any details about now. Apparently there is a rather convoluted process for getting my passport records from the State Dept (which involves going to a notary, wherever you can find one in the UK!), but I'm wondering how crucial this bit of the form is. Can I just make an intelligent guess of my old passport details (e.g. year and place of issuance) or do I really need to get them from the State Dept?

It seems ridiculous that after getting almost to the finish line I'm having such trouble crossing it!

Thanks very much for any helpful advice/comments.

I'm only guessing here, but if you don't have the information, you don't have it.

I let my first US passport expire and then misplaced it for about 20 years before I felt the need to get a new passport.  I was told because I didn't have the details about it, not to worry about it and got a new US passport with no problem...if the US isn't/wasn't keeping track of my old passport details, I would imagine the UK isn't going to be too worried about it either...but, as I said, I'm just guessing here!

(My old passport miraculously re-appeared a few years after that and I keep it in a safe place now, just in case.)

Congrats, btw, on your Britishness!! 

When you applied & got the CUKC (Brit citizen), look at what you had to provide &  whatever the UKBA/Brit government authorites gave you as a document to say that you are a Brit should do it for a passport application as confirmation.

Being a Brit by birth, for me its confusing applying for the darn thing as it would someone who is applying the first time, in fact my kids born outside the UK was even worse.

After doing it once for my eldest the second child was a cake walk

Just give them everything that you have, of course there isn't anything you can do (as Juliloew says) about lost passports which I really believe they will not ask you to find

Go for it & apply on the basis of all that you have confirming that you are a CUKC