London City Mission has bid farewell to its chief executive the Reverend Dr John Nicholls after 20 years with the organisation.

Dr Nicholls first joined the organisation as training director in 1993, a position he held until 2005 when he became chief executive.

Roger Gadsden, one of LCM's ministries directors, said Dr Nicholls had steered London City Mission with "immense wisdom".

"He has given us a confidence about the value and importance of what we do, in terms of the role the City Mission can play in our society and our city. I can't express enough the privilege that I've had in being part of John's team," he said.

Dr Nicholls said thanked the LCM family for their prayers and encouragement over the years.

"It has been a great privilege to work in a Mission that God has used so significantly, over such a long period of time," he said.

"I've spent much of the last month visiting the missionaries on their districts. Once again I've been excited by the sheer range and number of the contacts they have made, by the way God has given them such skills, patience and boldness in all kinds of situations – and by God's amazing grace that uses even the weakest of his servants to do great things."

He added: "May God's grace, love and power continue with the London City Mission every day!"

Dr Nicholls is being succeeded by Graham Miller, currently serving in East Asia with Crosslinks. Miller takes up his position as chief executive on 1 October.

Alan Black will serve as interim chief executive in the meantime.

Following his appointment, Miller said, "After spending nine years serving in East Asia, I am very excited to be able to return as a missionary to London.

"I am awestruck but also very grateful when I think of the faithful saints who have gone before me in this role. I remind myself that our great God can use even a cracked, clay jar like me to carry the glorious good news of Jesus Christ to London's unreached."