Obviously if employees of the ltd company were found guilty of fraud of large amounts of money they too would probably get a custodial Sentence.
The two guiding factors in the sentencing are the degree of culpability and the level of harm to the public revenues. Culpability in this case will be determined as medium (I would be surprised if it were high) the level of harm is yet to be assessed, if it's in the millions it will be bad news for those responsible.