The first appearance of THE ANCIENT ALLAN was as a serialized novel, published in Cassell’s Magazine from March through October 1919. Albert Morrow created 18 illustrations for the serialization.
McKay, Scott, and Whatmore claim that Cassell and Company published the first edition in book-form in London on February 12, 1920. Only 8 of Morrow's 18 illustrations are in this edition. There are no ads at the end of the book. McKay and Scott claim that 12,500 copies were printed. The last page has a date-code of 120 (January 1920).
Higgins claims that Cassell paid £400 ($39,000 in 2020 dollars) for the serial rights, and £750 ($73,000 in 2020 dollars) was advanced for publication in book-form.
Longmans, Green and Company published the first American edition March 25, 1920. McKay and Scott both agree on the publication date in New York. Longmans claims it published this novel in February 1920 (see below). The American edition has a full-color frontispiece by Enos B. Comstock. The ads at the end of the book are not dated.
See the VisualHaggard.org page dedicated to the illustrations found in various editions.
I do not own the serialization of this novel in CASSELL'S MAGAZINE and have only seen the first issue of the serialization
My copy of the Cassell British first edition original dust jacket, restored
Another copy of the Cassell British first edition original dust jacket
Below: A copy of the Longmans, Green American first edition next to the Cassell British first edition, neither in my collection
My copy of the first British edition, which HRH signed for Mrs. Pitt
According to Sumner and Stillman, booksellers out of Maine: "Mrs Sarah Pitt was a writer of novels meant for children, or at least young adults -- for whom Cassell was likewise the UK publisher; she had been quite popular during the years 1881-1900."
I am not certain that they are correct, but their theory sounds reasonable.
Below: the British first edition frontispiece and title-page
Date-code of 120 (January 1920) on the last page
Below: a variant of the British first edition
Below: a signed copy of the British first edition
Below: A Longmans, Green American first edition with original dust jacket, sadly not in my collection
Below: my copy of the American first edition original dust jacket
My copy of the American first edition
I also own another copy
Below: The frontispiece and title-page of the first American edition.
Also below: The printing history from a 2nd printing, which shows the first printing was in February 1920, not March 25, 1920, as McKay and Scott claim.
Ads at the end of the Longmans, Green first edition cover many of HRH's novels
Below: a British reprint published by Cassell
I sold this one to another collector