So when I saw fedora 33 was available, thought I would try that and hopefully side-step the issue. But I now get:
Unable to upgrade to Fedora 33:
package jenkins-2.263.1-1.1.noarch cannot be verified and repo jenkins is GPG enabled: failed to lookup digest in keying for /var/cache/PackageKit/33-metadata/jenkins-33-x86_64packages/jenkins-2.263.1-1.1.noarch.rpm
Any thoughts on what has gone wrong ad needs to be reset would be welcomed
First, always run a “dnf upgrade --refresh” to verify no problems exist before you attempt a system upgrade to later version. Failure to do that might bite you later.
Second: it is a good idea to disable third party repos before doing the system upgrade. Your error is from a 3rd party repo that appears to not be current in updating for F33 compatibility. Disable that repo and see if the error goes away. It can always be re-enabled after the system upgrade is completed.
The error with upgrading to 32 looks like a mirror issue and likely was or would have been resolved in a day or two.