Merging Neil's most recent work from walton branch to main

[ThomUK]

2 tests commented out (function is no longer vectorised)
Cran checks not passing (1 error, 3 warnings, 2 notes)

Propose merging to main to allow clean re-start to issue fixes from a single branch (main)

[ThomUK]

Closing PR as discussed in project meeting. Neil to merge additional branches and raise new PR.

[Lextuga007]

@ThomUK Just to tie this in with the failed gh action, did it fail from this PR which isn't being used now? Thanks

[ThomUK]

Hi @Lextuga007, Neil is working at pace developing the package. His work feeding this PR was branched from main a long time ago, and my merge conflict resolution skills were not sufficient to sort it all out. Neil has since done more development locally (features and bugfixes), so he's going to merge all that together and make another PR which will replace this one.

[Lextuga007]

Great update! I wasn't sure if the gh action needed an issue but this sounds like it was just related to the PR. Also answers a query in the Slack about the stability of the package and use which is great, thank you!