According to intelligence writer Stephen Dorril was amongst the most important of the MI5 officers who died:
- The key person of the six and a totally irreplaceable loss to the Service and the countering of the IRA in particular. As I understand it, Maltby - on his second tour of duty in the province - ran the unit monitoring the IRA's collecting and laundering of funds. During the seventies, when MI5 had no responsibility for the IRA, only the Loyalist terror groups, Maltby ran a one man operation keeping track of IRA funds. It would be difficult, if not impossible, to replace such an institutional memory. It is fortunate for MI5 that the cease-fire has made that, for the moment, unnecessary.
The unit Dorril describes may be the Anti-Racketeering Unit (Northern Ireland)