The charges follow an extensive investigation of the company and its subsidiaries by the Department of Trade and Industry and the Serious Fraud Office.
The two were charged along with Anthony Cole, the former chairman of Bestwood, who faces 20 charges of theft, fraud and perjury. He pleaded not guilty to all charges and is due to face trial next year.
Collins pleaded guilty to attempting to commit an offence of false accounting, contrary to section 17 of the Theft Act, in that he sent a letter to BDO Binder Hamlyn, the auditors of Bestwood, saying that Guy Puckle owed pounds 300,000 to the pension fund of a subsidiary of Bestwood when it did not.
The prosecution accepted that as the letter did not get to Binder Hamlyn, he could not have actually committed false accounting.
Southgate pleaded guilty to a charge of false accounting, in sending a letter from his firm, Osborn Southgate and Co, to Bestwood Securities saying that pounds 400,000 had been paid to it from Mamro, a Jersey company, when it had not been.
Collins pleaded not guilty to a charge of theft and Southgate pleaded not guilty to three charges of fraud and conspiracy to defraud. These charges are to lie on file until the conclusion of any proceedings against Mr Cole.
Collins and Southgate are due to appear in court next on 6 November for sentence.Reuse content