[1] He received his earliest musical education at Westminster Cathedral choir school, where he acted as assistant to George Malcolm at the organ from the age of 12.

He also collaborated with the London Mozart Players, the Wren Orchestra, the Belgian Radio Choir and the BBC Singers.

In 2006, Mawby was awarded by Pope Benedict XVI the Knighthood of the Order of St. Gregory, "in gratitude for past and continuing services to church music".

His Ave verum corpus for choir and a setting of Psalm 23 won fame in the recording by Charlotte Church.

[7] In 2002, his Prayer of Forgiveness was awarded "Top Honors" in the competition "Waging Peace Through Singing" in the US state of Oregon.

[7] A Te Deum for soprano solo, chorus, organ and brass ensemble was premiered in Cambridge in 2006 to mark his 70th birthday.