In the case you mention, it's difficult to be concise without all the facts of course, as I have attempted to mitigate on here before? However, that said the Convicted did at that time, with malice aforethought defraud the public purse of £12,000 pounds, thirty years ago. He therefore 'obtained a pecuniary advantage by deception'.
The Law specifically on 'Benefit Crime/Fraud' (his offence today) states;
... The CPS took on the prosecution of DWP criminal investigations in 2012, and until the restructure of fraud work in July 2018, these cases were handled exclusively by the Specialist Fraud Division (SFD). Since the restructure, only DWP cases meeting the SFD referral criteria continue to be prosecuted in SFD, with the others handled by the specialist fraud centres in CPS Wessex, Mersey-Cheshire and Wales.
Section 128 of the Welfare Reform Act 2012 (WRA) permits the Secretary of State for Work and Pensions and persons providing services to the Secretary of State to disclose social security information to the Director for Public Prosecutions (DPP) for the purpose of the functions exercised by the DPP.
Section 129 of the WRA 2012 prescribes the use that can be made of social security (including tax credit) information disclosed by the Secretary of State under Section 128 and creates an offence of unlawful disclosure. CPS prosecutors disclosing social security information in accordance with the DPP’s functions and CPS policies will incur no liability...
In sentencing currently, such values as;
Did the offender plan the crime to deprive, was he a 'professional' (scammer con-man)?
Was there a victim and were they cruelly susceptible (elderly or disabled)?
Was any physical harm proffered?
Did deliberate concealment occur?
Was the motivation greed or political (terrorism)? including identity deceit?
Was embezzlement or detinue involved?
Was encitement to others to become inclusive made?
Any previous offences?
How long did he persist with the fraudulent benefit claim?
This list is not exhaustive, but it seems to me none of the above were applicable to your friend.
A prison term of up to 10 years can apply for this offence. The use of a custodial sentence with suspension seems right and the term I consider to have been something I would have handed down myself - NB please at that time, within the sentencing guidelines applicable? Although I expect he actually never served any time, remand etc being taken into account? I would conjecture that he may have also been severally pursued for bankruptcy in a civil arena by a preferential creditor and the bench took these circumstantial fiscal chastisements into account as well. I presume no order was made for costs?
Today he could under new guidelines to be handed a fine and a non-custodial sentence.