In the past I have remarked that Pakistani policy has been a series of 'stop, start' moves and this incident has added a 'review'. One begins to wonder what is going on when you read this (my emphasis):
The committee also said the United States would be asked to vacate, within 15 days, the Shamsi air base, which the US has used to launch drones.

However, our correspondent notes that Pakistan has made a similar demand before and the base may already be empty.
Link:http://www.bbc.co.uk/news/world-asia-15905777

Note a few days ago the British Home Secretary was in Pakistan saying:
..the UK and Pakistan share a "powerful interest" in fighting extremism and terrorism....the ties between the countries "feel stronger than ever" after meeting Pakistan's Interior Minister Rehman Malik during a visit to the country.

"Pakistan is on the front line and you have made tremendous sacrifices," Mrs May said.
Link:http://www.bbc.co.uk/news/uk-politics-15868852

I would contend that this episode is a good illustration that Pakistani politics, notably popular antipathy to the US, quickly overwhelms such polite, diplomatic sound bites and international co-operation is oh so fragile. This last UK ministerial visit is I readily admit peripheral to Pakistani national security policy; I doubt if ISI and the Army met her.

We are still waiting for the ISAF investigation to report before a judgement can be made.