Key jammed in ignition switch

[ShaneHobson]

My key is jammed in the ignition switch.
Assuming the key barrel has 4 positions :
Lock
Acc
On
Start

The car was running, I stopped and went to turn the engine off.
The key barrel turned from On to Acc, but won't turn back to Lock.
In normal operation the key barrel needs to be pushed inwards before it will rotate back to the Lock position.
It will still push in ok, but won't rotate back to Lock position.

Before I get a locksmith to disassemble the key barrel, I wonder if there is an electronic interlock of some sort that would prevent the key being turned from Acc position to Lock position.

Thanks