Greetings! This is a most interesting question before us, and it certainly does sound logical (in light of what OP has already put forth in their contextual bit of the question) that British historians prior to the First World War treated German history in much rosier light than other continental historians (or indeed, the Germans themselves!) viewed it. It also therefore, stands to reasons that following the War Guilt assigned to the Germans (in actuality a gross misrepresentation of Article 231 in the Treaty of Versailles), this historiographical thinking in Britain saw a "divorce" to cheekily continue OP's analogy of family connections. However, let us dissect this question a tad more and see if that really was the experience of British historical circles after the horrors of the Great War. It is necessary to first note however, that this response will fall short of actually analysing primary sourcework on what British historians in the period leading up to 1914 wrote on German history (though efforts were made, blast it JSTOR...).

To begin this investigation, a quote from Margaret MacMillan which illustrates not only how pre-war British historians viewed their German counterparts in high regard, but also how other areas of British academia and culture respected the continental Teutons:

"Each found much to admire in the other. For the British, it was German culture and science. German universities and higher technical schools became models for British educators. British students in such fields as medicine had to learn German in order to read the latest scientific work. Germans dominated the important fields of biblical scholarship and archaeology, and German history, with its stress on archival work, the amassing of facts, and the use of evidence was felt to show the past 'as it really was'".

Note: the 'as it really was' comment is an allusion to the Rankean school of historiography, which was founded mainly by German historian Leopold Ranke, whose signature phrase of '*wie es eigentlich gewesen' (*how it actually happened) is often interpreted, as it was back then, to be a call for greater adherence to empiricist principles in the discipline of history.

Perhaps a primary source to help substantiate MacMillan's claims. Consider this curt yet illuminating remark by eminent British historian Sir John Seeley, who was Regius professor of modern history at Cambridge from 1870 to 1895:

"As a rule, good works are in German."

Prior to the First World War, it certainly seems as though OP was right in assuming that German historiography occupied a very high station in British historical circles right up until 1914. In particular, British historians in institutions of higher learning valued the German-born principle of Wissenschaft (or "science", as it roughly translate to English). This ethos of learning emphasised an empiricist outlook on all things, and the past was no exception. Many British historians rallied to the "call" of Rankean scholars and their adherence to portraying the facts and little else. Herbert Albert Laurens Fisher, another well-known British historian of the pre and post-war era, remarked after the war that:

"To sit at the feet of some great German Professor... was regarded as a valuable, perhaps as a necessary passport to the highest kind of academic career...The names of the German giants, of Ranke and Mommsen, of Wilamowitz and Lotze, were sounded again and again by their admiring disciples in British lecture-rooms."

Note: Theodor Mommsen was another German giant of historical writing, whose monumental work A History of Rome is well-known in classicist studies. Ulrich von Wilamowitz-Moellendorff was his counterpart on Ancient Greece, whilst Rudolf Hermann Lotze was a pioneering philosopher and theologist who founded Theistic Idealism.

The list of quotes praising the German historiographical field (as well as other academic disciplines) goes on and on, and each one can be traced to a famous British historian of the time as well. It would not be too far off the mark to assume, in light of such utterances, that the perspective of German historiography by British historians prior to the First World War was one of admiration and respect.

Racial Anglo-Saxonism, which impacted all manner of sociopolitical writings and attitudes in late Victorian England, reinforced such a strong connection to Germany. Without going too far in-depth on this theory, the four basic beliefs of this myth in 1900 are as follows:

1. Germanic peoples, owing to their unmixed racial origins and universal civilising mission, are inherently superior to all others,
2. The English are of mainly Germanic origin and their history begins with the arrival of Hengist and and Horsa [two legendary brothers said to have led the Angles, Saxons, and Jutes in their invasion of Britain in the 5th century] at Ebbsfield, Kent, in 499,
3. The qualities which render English political and religious institutions the freest in the world are an inheritance from Germanic forefathers,
4. The English, better than any other Germanic people, represent the traditional genius of their ancestors and thereby carry a special burden of leadership in the world community.

Historians were among the most numerous proponents of Anglo-Saxonism, and some of them helped to give rise to the theory that the Anglo-Saxon peoples (represented in the early 20th century by the Germans and British) were a united and superior race. Sharon Turner, John Kemble, Lord Macaulay, Thomas Arnold, Thomas Carlyle, the list of reputable British historians who supported and propagated the myth of Anglo-Saxonism reached far and wide.

In the textbooks of the age, such racial motifs were common as well. But they were also notably Prussocentric, portraying the German Empire which had come about in 1871 as a whole "new" Germany superseding the "old" one. Emily Hawtrey's A Short History of Germany (1904) does this most prominently, with Hawtrey even being sympathetic towards the Prussian aims and methods, portraying the Franco-Prussian war as the fault of the French, who unwillingly initiated the conflict which would united the German states. James Headlam-Morley, who was an expert on German history, showed similar sentiments in his work Bismarck and the Foundations of the German Empire (1899), as did William Harbutt Dawson in his The Evolution of Modern Germany (1908). Perhaps most interesting of all are the following extracts from W.W Tulloch's The Story of the Life of the Emperor William of Germany (1888):

"If Prussia was to become great, it would be by means of her army."

"[Wilhelm II] is the incarnation of duty, and the soul of honour."

"War between France and Germany was only a question of time and opportunity. France was eager to try conclusions with a state which threatened to usurp her hitherto unchallenged sway as the greatest power on the Continent."

Even during the Anglo-German Naval Race of 1906-1912, historians actually served as conciliatory mediums, who produced a litany of new works and revised editions of older ones which aimed to lessen Anglo-German naval tensions. In other words then, up until the outbreak of war in 1914, British historians were very much pro-Prussia, pro-Bismarck, and pro-Germany.

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