Eventually I found out it is because Git is choking on one the line endings in some files. When trying a commit of these files I would see a whole load of errors fly by such as ‘trailing whitespace’ and “you have some suspicious patch lines”. Googling around I found three answers, but I could only fully understand two of them.

Firstly, the approach I took, was to run the command chmod a-x .git/hooks/pre-commit in the git repository.

The other approach, which I found here says to edit the pre-commit file above and comment out the lines:
if (/\s$/) {
bad_line("trailing whitespace", $_);
}

Which would mean changing it to:
#if (/\s$/) {
#bad_line("trailing whitespace", $_);
#}

Hope that can help someone!