When I produced data showing Circumstances could be coordinated with hypotactic clauses and nominal groups with projections the response was to falsify the data and to add missing features a la TG so that the theoretical tenet that only like elements can be subordinated was upheld at all costs.
I told the list the problem and that there was a need to solve it on various occasions and when it took my fancy.To give examples of both : )
 To be clear, a circumstance is a class of element of function structure at clause rank, whereas a hypotactic clause is a class of form. In SFL theory, co-ordination is the relation of paratactic extension that obtains between units of form at the same rank.
On the one hand, Bartlett confuses function with form; that is, he confuses two distinct levels of symbolic abstraction.
On the other hand, if the co-ordination is held to obtain between a clause and the formal realisation of circumstances, as a prepositional phrase or adverbial or nominal group, then Bartlett confuses clause rank with group/phrase rank; that is, he confuses two distinct levels of composition.
 To be clear, a nominal group and a projected clause are distinct levels on the rank scale. The confusion is again one of level of composition.
 In SFL, such phenomena are accounted for by the cohesive system of ellipsis (Bartlett's "missing features"). Halliday & Matthiessen (2014: 635):
Ellipsis marks the textual status of continuous information within a certain grammatical structure. At the same time, the non-ellipsed elements of that structure are given the status of being contrastive in the environment of continuous information. Ellipsis thus assigns differential prominence to the elements of a structure: if they are non-prominent (continuous), they are ellipsed; if they are prominent (contrastive), they are present. The absence of elements through ellipsis is an iconic realisation of lack of prominence.
 To be clear, proposed theoretical changes that arise from theoretical misunderstandings and result in theoretical inconsistencies do not improve the explanatory power of a theory. The larger problem here is that Bartlett is taking a syntactic perspective, which is the opposite of that from which SFL was theorised, as Halliday (1994: xiv) explains: