Thanks for the reply. I did the Malwarebytes bit and it found 92 issues 2 were trojans. Strange that Avast’s scan didn’t pick these issues up. I saved the issues to quarantine - should I now delete them?

I obviously used my browser to post this reply and the ‘transfercom.net’ malware alert has now gone. I have attached the logs from Malwarebytes for interest (!).

I think running that software has done the trick - many thanks for your advice.
Ricardo