"But the real reason is that attacking the Islamic State would mean allying ourselves with Bashar al-Assad, the tyrant of Syria, who, only a year ago, David Cameron wanted to launch a joint strike against."
http://www.dailymail.co.uk/debate/article-2754273/Why-deals-monsters-writes-SIMON-HEFFER.html
That is the standard of journalism the West depends on.
Obviously you can attack ISIS and not support Assad.
But his rhetoric is out of date, as anyone who saw/listened to Obama's address to the US on Wednesday would realise, when Obama ruled out working with Assad ( thus ruling out UK-Assad collaboration).
{Please note at 5 minutes 40 seconds into the speech when Obama says "..in June I deployed several hundred service members to Iraq to assess how we could best support Iraqi security forces..." ..... yet the sudden presence of ISIS 'took everyone by surprise'.}
Quite a potentially dangerous speech as it rules out 'no hiding place' ... "we will hunt down terrorists that threaten our country wherever they are.."
http://www.nytimes.com/video/world/middleeast/100000003107090/obama-addresses-the-nation-about-isis.html