"180 and backtrack" makes more sense to me, the term backtrack makes it far clearer, without it I still maintain that the instruction is less clear than it could be.
And checking my copy of CAP 413, it doesn't require "degrees" universally when giving a heading. "heading 180" or "track 180" would both be legitimate calls according to that.
Here's an instance; Let's say I've just landed at Blackpool on Rwy 10, and am down to taxi speed about mid-runway - that would be just short the C2/C3 holds. I am given the instruction "turn 180, exit second right to hold on the 13 numbers".
I could (and bear in mind, I'm at the end of a flight, so my brain is at-least slightly addled) potentially put two interpretations on this.
(1) Backtrack 10, turn down Rwy31,
(2) Turn south onto taxiway C, then turn right all the way down 31.
The former is almost certainly the correct and more appropriate interpretation - but in that case why not just say "backtrack 10, turn right onto Rwy31, hold on the 13 numbers"?
G