Recently installed NHSbuntu on an SSD and added Skype but kept getting the following error when trying to run 'apt update':
W: GPG error: https://repo.skype.com/deb stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 1F3045A5DF7587C3
Thanks to QwertyChouskie over at this thread for the answer:
'curl https://repo.skype.com/data/SKYPE-GPG-KEY | sudo apt-key add -'
