Any person with any semblance of intelligence can see that the Iranian government compulsively lies and creates propoganda.
Now let's think for a moment who has more to gain/lose by not telling the truth. The soldiers who happen to lie- ALL of them with a corroborated fictional tale, or the Iranian government that does not want itself portrayed as brutal and deceitful in the eyes of the world?
There is a propaganda from both sides.
I don't agree that Iranians have much to lose. They are hated anyways regadless on what they do. The soldiers have more to lose. In some Western media there are questions on how they could so quickly admit they were wrong. It's embarassing. And the British government has apologized admitting that that the soldiers were arrested in the Iranian wtaers.