One good solution would be to apply on a letter head, but the signature should be of a person without mentioning his designation or post. This way the applicant can always claim that he has applied a s a "citizen" and that the letter head is being used only for the purpose of giving a address and number for reply.
There is a decision of the
CIC which allowed such a appeal.
I will search for it and post it here.
As Ganpat pointed out, better to be prudent in such matters.