Hong Kong stopped tamping passports in 2013. They were giving out these little paper slips that they are supposed to staple inside your passport. Unfortunately the IO at HKG didn't staple mine so it fell out over time.
Hence I can't prove what date I entered HKG for the purposes of my SET(O)
These days no one in the UK gets paper airline tickets anymore (as they used to be, rectangular pieces of card - the good old days

So I have my e-ticket, but of course it is an email. I can print this, but will the caseworkers accept it?
I have no other way to prove when I left the UK for this holiday.
Thanks