Checking this out it is quite understandable that the Tories are supporting the Government on there not being an inquiry.They could be implicated in huge corruption charges.Remember the deal was struck in 1985 and any inquiry could I suppose lead to the then government members being investigated. The excuse that an inquiry would be a national security risk and lead to deaths of UK servicemen is hollow. It seems that if you shout national security over the inquiry it can be filed away and forgotton forever. The inquiry would reveal several things. Firstly, if bribery happened (and they http://www.caat.org.uk/campaigns/controlBAE/bae-agm-2008.phpseem to think it does) and secondly , the government dealings and relationship with a totalitarian feudal regime such as Saudi Arabia.
It seems the Government is protecting its allies at all costs. In this case the Tories and their friends in the Saudi Government.