City of London police have not confirmed whether the man in question is Peter Carron, managing director of Primrose.
The man has been released on bail without charge.
The south-east London man was arrested on suspicion of fraud and abusing a position of trust.
Earlier in the year Primrose Associates was placed into liquidation, leaving behind debts of £5m.
KCBS was appointed liquidator for the mortgage brokerage after a meeting of creditors.
It is believed the money which was invested in Primrose was subsequently used to develop technology systems at Evaluate.
Mortgage Strategy could not reach Carron for comment.