She does give a feck but not about her majority. As I've said before, about the only thing Diane could do to lose her seat is die.
She's in the shadow cabinet because Labour's front bench resigned en masse when Jeremy became leader and very few of Labour's second division were willing to replace them. Not, I suspect, due to any high minded political principles but rather out of fear that their careers would be damaged through association with Marxists, anti-Semites and terrorist sympathisers.
This left Jeremy trying to assemble a Premiership squad from politics' answer to the Vauxhall Conference League. That's why people like Diane, Colonel Thornberry and John McDonnell are sitting on the front bench. Nobody else wants to play on Jeremy's team.
Of course, that's not how Diane sees things. Diane stood for Labour Party leader in 2010, compared herself repeatedly to Barack Obama and spoke openly about what she would do when she was Prime Minister. Coming last with 7% of the vote did nothing to curb the woman's arrogance.
Inside Diane's head, she is a potential Prime Minister, a global statesman and a worthy heir to Nelson Mandela's legacy. In the real world, 30 odd years of long lunches, epic sickies and falling asleep in meetings has caused whatever wit and intellect she had to atrophy.
This is why she gets her arrse handed to her almost every time she appears on TV and why she is becoming a national laughing stock. Despite her efforts to redefine the word "racist" to include anybody who disagrees with her, the mess she is in is entirely of her own making.