May not be. I thought that the changes to the CCA legislation regarding electronic application came into effect from 2004. So your application in March 2003, will be under the previous CCA act. This will mean that to enforce the debt, the creditor or owner of the debt, would need the original agreement to take to court. Egg should have posted you the CCA to sign and return, but of course at the time they did not. Be careful though, as there have been cases where creditors/debt owners, have enforced debts using reconstituted agreements, with evidence about the debt. If you did defend such action, you would have to do a bit of research about how you would defend or employ a solicitor.
If you want more information specific to Egg agreements, suggest that you post to the Community Action Group forum, where there will be information/replies which might help you further.