In 1998, he spent an extended semester at The College of William and Mary in Virginia, USA, as Visiting Professor of Music.
Subsequently he took early retirement due to disenchantment with the tertiary educational system in the UK; he was initially awarded the title of Emeritus Professor of Music, though he later relinquished this post.
During his academic career Nicholls gave many presentations – both refereed and guest – in North America, France, Germany, Mexico, Australia, Taiwan, and the United Kingdom.
Until 2000 he was also active as a composer, and his works were performed and broadcast in the United Kingdom, Europe, America, Australia, and South Africa.
Since retiring, Nicholls has spent his time primarily engaged in activities rendered impossible during his working life: gardening, cooking, reading non-academic literature, and building a large-scale model railway.