You can always mention that you were inspired or interested by meeting someone - that never needs permission (as long as you aren't quoting them or commiting them in some way). But, in this case, it's probably not smart to mention the name for a few reasons
1) It sounds like it was a long time ago
2) It doesn't appear like a very strong relationship
3) Most importantly it sounds like the interview wasn't related to your interest in consulting, Usually people talk to current consultants in a recruiting context, and then it is more appropriate to say "i spoke to so-and-so about x,y,z in the consulting industry, i got interested, etc. etc."
Rule of thumb - if they were to mention your name to the partner, would they remember you? If yes, then it's okay - if no, I'd not do it.
Sri