Having reached the final hurdle of uploading months of work from MAMP to my online host, it turned into a nightmare.
Despite some reviews suggesting that bad stuff could happen (everything should be backed up anyway), I had little choice but to bite the bullet.
For some reason a couple of links to Localhost still existed after the first pass, but a second pass fixed it 100%.
3500+ links to Local host successfully replaced within 5 minutes of downloading the plugin, and i have not yet seen any sign of adverse effect.
Brilliant. Thank you