Also, the leading zeros in the array may be the padding at the end, as some other examples contain "128" at place 2, so I think I need to include them. But that's easy enough.
0, 0, 108, 65

Numbers are correct, as I've now manually successfully decoded it.
In terms of documentation, I've made and coded these sensors myself, I just didn't entirely understand how the data was encoded with the library (RadioHead ASK).

Now just need to figure out a command line binary to IEEE 754 floating point number conversion.

Bash doesn't do floating point, but I still expected it to be a simple case of calling bc or something, but nothing useful comes up from relevant searches.

Guess you'll have to convert your manual steps to Perl or Python?

Yeah, seen similar. Was wanting to use bc. Now looking at some other simple programs, C++, Perl or Python should handle it, then feed it back in.

Done, decoded using some simple python.