The correspondence between four-dimensional {mathcal {N}}=2 superconformal field theories and vertex operator algebras, when applied to theories of class {mathcal {S}}, leads to a rich family of VOAs that have been given the monicker chiral algebras of class{mathcal {S}}. A remarkably uniform construction of these vertex operator algebras has been put forward by Tomoyuki Arakawa in Arakawa (Chiral algebras of class {mathcal {S}} and Moore–Tachikawa symplectic varieties, 2018. arXiv:1811.01577 [math.RT]). The construction of Arakawa (2018) takes as input a choice of simple Lie algebra {mathfrak {g}}, and applies equally well regardless of whether {mathfrak {g}} is simply laced or not. In the non-simply laced case, however, the resulting VOAs do not correspond in any clear way to known four-dimensional theories. On the other hand, the standard realisation of class {{{mathcal {S}}}} theories involving non-simply laced symmetry algebras requires the inclusion of outer automorphism twist lines, and this requires a further development of the approach of Arakawa (2018). In this paper, we give an account of those further developments and propose definitions of most chiral algebras of class {{{mathcal {S}}}} with outer automorphism twist lines. We show that our definition passes some consistency checks and point out some important open problems.