Many church organs, including the previous instrument in Exeter Cathedral, were vandalized or destroyed during the English Civil War.
During this period, Loosemore was employed primarily in repairing organs and building other keyboard instruments for private ownership.
With the restoration of Charles II to the throne in 1660, Loosemore was commissioned first to repair the old organ in Exeter Cathedral, and then, in 1662–1663, to build a new one.
Loosemore constructed at least two other organs during his lifetime, another in Exeter Cathedral for the choir school and one at Nettlecombe Court for Sir George Trevelyan.
After the marriage of his eldest daughter Joan to his assistant John Shearme in 1674 or 1675, Loosemore turned over much of his business to him and lived in semi-retirement.