With or without the A prefix, this morose instrumental renders equally well for keyboard or string quartet. It was composed by Thomas Tomkins shortly after the execution of Charles I, but not on the organ of Worcester Cathedral where he was organist because not long before, the instrument had been trashed. A quarter of a century earlier, Tomkins had composed music for the King's Coronation. Now he had seen everything he held dear, destroyed. All that was left was to write the funeral dirge, for his king, and for his life's work.
After the execution of Charles, although Oliver Cromwell was King of England in all but name, he took the title Lord Protector. The monarchy would not be restored until 1660, but the already elderly Tomkins never lived to see it; he died in June 1656.
Suggestion credit: Alexander Baron - London, England