MI5 and MI6 is involved very intensive since war on terror in Afg- Pakistan. Few years ago CIA, RAW, MI5, MI6, Mossad, Khad (Afghan) and russian agencies met in Afghanistan and decided their road MAP against Pakistan.
I add some links here which tasks british MI6 is completing in Pakistan:
First watch this clip why MI5's interests in Pakistan? Mirza Zulfiqar said something about it in this clip :
UK is no longer secret player in this anti Pakistan game of agencies. You might have read sometimes in news paper that Europes country(?) is behind some bomb attacks in Pakistan. It is UK.
What they are doing in Karachi: They are interested in Rehman Malik to carry on his games. Blood shed should not stop in Karachi. They knew every thing about Altaf Hussain but they keep him to use for the right time.
I am sure nothing will happen to Altaf Hussain due to Dr. Imran murder Charges. Some Jiala of MQM will stand up and will accept all charges and that he did without any involvement of Altaf Hussain. Altaf Hussain is an important player for foreign agencies and they will use him for proper time. Same tactic what they used in Lybia with rebells leader.
As i said: These all secret agencies are following that road Map fixed in Afghanistan against Pakistan.
MI6 in Pakistan:
http://qutaibaprotocol.blogspot.com/2011/05/uks-mi6-financing-terror-attacks-in.html
MI6 Pakistan’s decision to expel British military trainers from the country was taken in June 9 Corps Commander
http://ummatenglish.com/exclusive/2011/06/28/mi6-disguised-as-hizb-ut-tahrir-in-pakistan.html
MI5, MI6 and CIA involved
http://pakobserver.net/detailnews.asp?id=88974
Austrian Newspaper reporting about MI6 bombing activities in Pakistan.
http://www.krone.at/Nachrichten/MI6..._fuer_Al-Kaida-WikiLeaks-Bericht-Story-259134