What is the History between Tom Quinn and Tessa Phillips

I'm re-watching Spooks and the first scene between Tom Quinn and Tessa Phillips is the following exchange:

Tom: I thought we were supposed to share information. Do the words 'ports warning list' mean anything to you? She came in over six weeks ago, God knows where she's been.

Tessa: She was on a false passport to Dover from France and her name wasn't Mary Kane, it was Denise Marston. I'm not Mystic Meg, Tom.

Tom: No, Tessa, you're something else. [staring]

[Tessa sighs incredulously]

I know later on they have a lot of issues, but I don't recall this ever being explained, nor is it on the Wiki articles. Does anyone know what the history is between them that could explain the exchange? It certainly doesn't sound like it's completely her fault for missing it.