[Tallguy]

Maybe a small motor with a smaller impulse just to push it clear of the VLS cell? Would think that would be more reliable than a pneumatic push.

[Right Brother]

England tests new defensive missiles while it welcomes invading hordes of Muslims. Makes perfect sense.

[az_gila]

Maybe a small motor with a smaller impulse just to push it clear of the VLS cell? Would think that would be more reliable than a pneumatic push.

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It seems a physical piston is involved, then airborne missile is deflected in the correct direction, and the main motor fires.
A good description on wiki -

“...both use a “soft vertical launch” system, whereby the missile is ejected from a tube by a piston. A short booster uses squib thrusters to point the missile at the target before the main motor fires. The lack of toxic fumes on launch makes launches safer for users, avoids corrosion of the launch platform and the lack of exhaust vents allows the launch cells to be much more compact....”