The role – one of the most high profile in the civil service – reports to permanent secretary Bill Jeffrey.
He replaces John Pitt-Brooke, who has joined HQ Land Command, the body responsible for deploying the Army's fighting troops worldwide, as command secretary (PRWeek, 16 June).
"There are huge operational stretches for the armed forces at the moment; they are supporting many operations in many places," he toldPRWeek.
He will be responsible for the MoD's press operation, run by recently arrived director of news James Clark.
Ongoing issues include criticism over the provision of equipment to the armed forces, allegations of abuse at domestic bases, as well as at operations abroad, and complaints about low-flying aircraft during training.
MacDowall joined the DWP – which is expected to start recruiting for his replacement imminently –when it was set up in 2001. He oversees around 500 staff, including teams at organisations such as Job Centre Plus, the Child Support Agency, Disability and Carers Service and the Pensions Service. The DWP's own central corporate comms team has 300 staff, 100 of whom handle e-comms.
Before the DWP, MacDowall was director of comms at the Department for Social Security.
Before that he worked in comms at Nato's press centre in Macedonia during the Kosovo war. He also served in the Canadian army for 22 years, having emigrated to the country when he was ten.