Learn English – “Philippines” vs. “Filipino”

This is an interesting excerpt from Wikipedia:

After the invention of the printing press in the 1440s, English spelling began to become fixed. This took place gradually through printing houses, whereby the master printer would choose the spellings "that most pleased his fancy". These spellings then became the "house style". Many of the earliest printing houses that printed English were staffed by Hollanders, who changed many spellings to match their Dutch orthography. Examples include the silent "h" in "ghost" (to match Dutch "gheest", which later became "geest"), "aghast", "ghastly" and "gherkin". The silent "h" in other words — such as "ghospel", "ghossip" and "ghizzard" — was later removed.

It reminded me of an article I came across years ago, which explained the disparity between the pronunciation and the spelling of the English language, something not happening in other European languages I know, at least not to this extent. In essence, it claimed it is difficult for written forms of the language to change and follow the spoken changes, especially in English. I don't remember the reasons why, but this explanation was enough for me to understand why there are practically no rules for pronunciation.

As to why these odd spellings haven't been replaced yet, I know there are suggestions for it (not only about English, mind you, a big debate has been going on in France about the simplification of French spelling), but no decisions have been made so far.

This website says

It's the result of the same process (that is, erroneous pronunciation) whereby "learn" becomes "larn" in some (very) nonstandard American dialects. One feature of uneducated speech in England around the 1800's was a tendency to pronounce the "er" sound of words like "clerk" as the "ar" sound of "clark". The phenomenon was sufficiently widespread that the English novelist Henry Fielding used pronunciations like "sarvis" for "service", "sartain" for "certain", and "parson" for "person" in the speech of characters meant to seem vulgar or unintelligent. Due to the overwhelming influence of such people in England (that is, the uneducated), these previously unacceptable pronunciations eventually became standard for some words, like Derby, Berkeley, and clerk...
Source(s): J.C. Wells, Accents of English

So a more general sound change that took "er" to "ar" was present in some lower-class British accents when Henry Fielding wrote Tom Jones (ca. 1750). This 1849 dictionary found in Google books indicates that this pronunciation had for the most part vanished a hundred years later¹. The pronunciation now persists in only a handful of words:

Berkeley, clerk, derby, Hertfordshire, sergeant, varsity.

I take the liberty of including varsity here because it was originally short for university. However, university has reverted to the standard pronunciation, while varsity has switched to the phonetic spelling.

¹ Interestingly, the dictionary also says that many Americans pronounced sergeant with "er".