Their confrontations take them into the realms of detective investigation and science fiction, dealing with themes of time travel, historical events, and espionage.

The later, post-Jacobs title The Sarcophagi of the Sixth Continent provides insight into their early lives, and shows them making acquaintance – then beginning their friendship – during the time of the British Raj.

Colonel Olrik, the main antagonist, displays a combination of the characteristics and personalities of both heroes, but his exploits are typically negative, ending with disastrous consequences.

Furthermore, the structure of the books' storylines are often similar: in the beginning, certain unseen and significant events have already taken place – in The Yellow 'M', for instance, the antagonist of the story, 'Guinea Pig', has already committed various daring acts of theft on a grand scale, and readers only learn about this upon seeing Mortimer reading a newspaper.

Blake and Mortimer are frequently shown to be residing in a shared home, in adjacent apartments, the same manner as Sherlock Holmes and Doctor Watson.

Many francophone comics share this basis of confirmed bachelors who live together, including Tintin and Captain Haddock, Asterix & Obelix, Spirou & Fantasio, and Tif & Tondu.

The settings of many of Jacobs' stories are contemporary, based on real-world events and environments, and as such the first few titles of the series present a look and feel reminiscent of the 1950s, while later instalments showcase a political climate comparable to the 1970s.

These books are still firmly set in the middle-to-late 20th century, and include many new regular supporting characters, most notably Blake's colleagues in the security services.

Its storyline was provided by famous scenarist Jean Van Hamme, and specialist draughtsman Ted Benoit (whose Ligne claire drawing style resembles that of the late Jacobs') was contracted for the artwork.

Purists, partial to the original plotlines of those penned by Jacobs, immediately objected to the choice of Van Hamme and, upon publication, went on to discover the feature of some of his typically trademark plot twists, taking an instant dislike to his contribution.

The elements of science fiction, prominent in earlier books by Jacobs', were noticeably absent from this new addition, which contained a strong focus on espionage.

As an interim solution, writer Yves Sente and artist André Juillard were contracted to publish another adventure, The Voronov Plot (1998) containing prevalent themes of the Cold War.

Later on, Van Hamme and Benoit completed work on their book, The Strange Encounter, which appeared in 2001, and concerns the heroes' confrontation of mysterious alien creatures.

In 2008, Sente and Juillard also released another book in the series, The Gondwana Shrine, chronologically following the events of the previous two volumes, The Sarcophagi of the Sixth Continent parts 1 and 2.

The jokes contained include: Two additional volumes of "Les Aventures de Philip et Francis" have followed, Le Piège machiavélique (2011) and S.O.S.

It features a British agent, Sir Francis Flake, whose friend (based on Mortimer) gets drunk on the announcement of Indian independence.