I've no way of verifying this at the moment, so usual caveats apply:
Jules
@ThatStupidMan
All 3 Brexit planning ops:
#Yellowhammer: base scenario for No Deal
#BlackSwan: worst case scenario for no deal (drug, food and energy rationing, Emergency Powers Act details and Martial Law planning)
#Kingfisher: financial support package for business
#r4today
https://twitter.com/ThatStupidMan/status/1172032366560329728However, it does seem plausible to me for several reasons.
IFFFF my understanding of the situation is more or less accurate (which it may not be), there are several "Operations" open, dealing with different angles.
It would also mean that some more "creative ambiguity" is at play in terms of downplaying the extent of preparation for potential domestic chaos to avoid public panic.
Yellowhammer does seem to be the base assumption of a no-deal scenario (whittled down to a one or two sentence summary).
The other two seem to be about operational planning (army/police, and emergency aid to selected business / service sectors), based on YH.
Meanwhile, Fuzz Wuzzy Hulk BoJo might well "negotiate" what the EU originally proposed (the NI proposal, as opposed to May's UK backstop) and claim victory.
If that happens, the UK could end up as the Kingdom of England.