I do recall that Lois Maxwell (the original movie Moneypenny) said that she always played the character as having been in basic MI6 training along with Bond, and that the two of them had had a torrid affair during it, but split up amicably at the end of training, because they knew they'd never have a chance to make a real go of it, with each one having a different career path ahead.

So it was more a couple of old lovers who still flirt and banter, but not seriously, just remembering the "good old days," than a case of her resisting Bond's advances.