It's interesting, Susan thinks, how she's got such a different experience of Lancelot to some of the other people here. He wasn't slow to sleep with her, and the only times he's seemed at all uncertain of his value to her is when his traumatic neuroses have got the better of him. It makes her fiercely glad that he's got that self-assurance with her. But still -

"I imagine it's more sexual uncertainty than it is social."