In 2009 he was invited by Archbishop Thabo Makgoba to be champion for the Anglican Church of Southern Africa’s Liturgical Transformation Task Team.
In his first sermon as dean, Aiken quoted Archbishop William Temple to remind his listeners that "the Church is the only cooperative society in the world that exists for the benefit of those who are not its members.
"[3] He spoke of his vision to nurture a generous and welcoming spirit at the cathedral which serves not just its own parish but also the wider city of Kimberley and the diocese.
His diocesan responsibilities included appointments as the Archdeacon of the Karoo (2011-2012) and as Titular Rector[clarification needed] of St Mary's, Barkly West, as well as his role as Canon Missioner for the diocese and as Vicar General (April 2012).
Following the retirement of Bishop David Bannerman at the end of January 2015, Aiken was licensed as Vicar General of the Diocese of the Highveld.