Thanks drxx. I see 33d now (it's a bit American to me) and yup, the parsing is fair I suppose but a bit hmm.
I see the parsing for 21a too now thanks. I had the right idea but got stuck thinking about 'cobber' as an Australian companion.
Just got to find the pairs to swap now. I've spotted a likely candidate for the final thematic word. I think I'll park it until tomorrow.