...Engineer visit today (that makes two who think one cannot connect with the modem alone, but I digress).
DrT
Please digress some more! Yours is the first post that I've seen in these forums where you are actually thinking outside (of) the (attached router) box.
Set your PC/MAC to DHCP (instead of PPPoE) when attached directly to the modem. If your DHCP client (PC/MAC/whatever) receives a private IP address, go nuts, and see if there's any useful info displayed at the DHCP server/gateway IP address, in particular, sync rates.
See
this.
I don't get FTTC until 06/2011 (although Openreach have now painted 'DSLAM' on the pavement adjacent to the existing cabs), otherwise I'd try this myself.
Good Luck!
JC