best method to post forms back

Hi, when posting the review forms back, which is the best way.
Recorded delivery or proof of postage?
Its been a while since we've had to do this and i think this discussion came up that time too.
As all the mail goes to Warrington mail hub I'm guessing a postal employee? would be sorting out the various letters to the relevant departments so not necessarily an employee from the DWP?
we did recorded delivery last time which we were able to track its progress but no recipient at the other end signed for it.
Would be interesting to hear your experience on this matter as obviously recorded delivery has a cost to it
Hopefully this all makes sense as we've had to hit the ground running with the late arrival of the review form but have got a two week extension.

I use guaranteed next day delivery, it's expensive but I consider it worth it. You do get a signature and a photograph as proof of delivery that way. I figure that the increased cost is less than the angst of a failed delivery and the hassle that would cause.

Thanks for your reply.
Worryingly it looks like a dammed if you do and dammed if you don't choice.
We sent ours recorded delivery as my wife's reminded me! and that went 'missing' for almost two weeks after it arrived, although i suspect that it was caught up in the backlog of replies?.
We will be taking your advice and send it recorded delivery

I would say for sure to send it signed for what used to be called registered post.
It's tracked from the moment it is handed over at the post office counter and if you log in on the Royal Mail website you can track every last part of its journey to delivery.
Usually it is delivered and signed and signature and name of personan who signed is available on Royal Mail tracking.
It does go to DWPs mailcentre usually Wolverhampton and scanned onto the system.
There's only once that I haven't had an actual signature but for sure the name of the person who received it was there.
(If you were to find no proof of delivery or at the very least the name of the person who took delivery of it, then as it's guaranteed signed for then you would need to contact Royal Mail to get the cost of postage refunded).
It's very rare for a signed for guaranteed next working day Royal Mail delivery to go astray.
It gives a lot of reassurance, so that's what I would say you should do post wise.