Problem was with specs repository, not on my side.
Found the answer here podfile gives an error on install, but since the question was less explicit on the symptom, I thought I would cross-reference it again in case someone was looking it up differently.
The answer is in the blog post here http://blog.cocoapods.org/Repairing-Our-Broken-Specs-Repository/ which explains the issue and the fix which is repeated below:
“You are going to have to manually delete any local copies of the Specs repository and re-clone the new version of the Specs repository. You can do that with the following commands:
$ pod repo remove master
$ pod setup
If you have any local commits or changes to the Specs repository which are not merged, you should ensure you have a copy of them. I would recommend that you manually copy these changes over and re-commit them. You can fix your repository without deleting, however, this is not a simple process, so we are instead recommending that you delete your copy of the Specs repository and any forks of it.”