Join Date: Oct 2001
Location: Falkirk, Scotland,VS Red, BA Gold, HH Diamond,UK Amex Plat
Programs: Master of the Privy Purse des Muccis
Posts: 19,244
Hi,
I did a similar routing in November 2016 ( LHR-PEK on BA then PEK-HKG on Cathay dragon)
There was a separate passage way to a international transit desk where they stamp your boarding pass then you got placed in the line after the main emmigration booths and before the booths prior to security.
No paperwork needed
Including security it took around 30mins from leaving the BA flight to being back airside in the departures hall.
Regards
TBS