My thoughts exactly. What can a fax do that a signed PDF attachment sent via e-mail cannot? I hate the way that lawyers and HMRC still insist on sending letters as well as their main method of correspondence. Philistines.
I had heard/read that Benson & his agent had stopped at a motorway service station to fax the signed copy of the forms through to Swindon. I guess it's possible that they didn't have access to anything to scan the document.