Npm publish E401 error

When I try to publish to github packages I get the following error.

roger@dragon:~/mtr-dashboard$ npm publish
npm notice
npm notice 📦  @marchwood/mtr-dashboard@0.0.1-alpha
npm notice === Tarball Contents ===
npm notice 777B package.json
npm notice === Tarball Details ===
npm notice name:          @marchwood/mtr-dashboard
npm notice version:       0.0.1-alpha
npm notice package size:  440 B
npm notice unpacked size: 777 B
npm notice shasum:        2285c27dd6bda4133ac047ca8f796ef5497c913e
npm notice integrity:     sha512-lL3jM6WTcMhw1[...]+WjDNYP7xUbxQ==
npm notice total files:   1
npm notice
npm ERR! code E401
npm ERR! Unable to authenticate, need: Basic realm="GitHub Package Registry"

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/roger/.npm/_logs/2020-08-14T08_42_58_745Z-debug.log

My npmrc contains rhe following.

//npm.pkg.github.com/:_auth_token=xxxxxxx...
@marchwood:registry=https://npm.pkg.github.com/marchwood

Anyone got any ideas?

Hey there @rogerjames99 thanks so much for popping into Community!

You may find the following answer from an NPM thread helpful.