Why did Old English use C while other Germanic languages used K?

• *The letter K comes from the Greek letter Κ (kappa), which was taken from the Semitic kap, the symbol for an open hand.' This, in turn, was likely adapted by Semites who had lived in Egypt from the hieroglyph for "hand" representing D in the Egyptian word for hand, d-r-t. The Semites evidently assigned it the sound value /k/ instead, because their word for hand started with that sound.

• In the earliest Latin inscriptions, the letters C, K and Q were all used to represent the sounds /k/ and /g/ (which were not differentiated in writing). Of these, Q was used to represent /k/ or /g/ before a rounded vowel, K before /a/, and C elsewhere. Later, the use of C and its variant G replaced most usages of K and Q. K survived only in a few fossilized forms such as Kalendae, "the calends".

• When Greek words were taken into Latin, the Kappa was transliterated as a C. Loanwords from other alphabets with the sound /k/ were also transliterated with C. Hence, the Romance languages generally use C and have K only in later loanwords from other language groups.

• The Celtic languages also tended to use C instead of K, and this influence carried over into Old English.

(Wikipedia)

I have read that until the time of grammarian guru, Quintilian ( 1st century AD.) "c" and "k" were both used in Latin. However, Quintilian put it about that "k" was not to be used, only "c". Therefore, the Romance languages, descended from Latin, hardly ever use 'k".

High German was not really developed until Luther's time and afterwards, when Greek was part of classical education. German academia having, broken away from the Roman church were reading old Christian documents in Greek, and perhaps decided that the more ancient "k" usage in their "newer" language gave it some cachet.

The really interesting "c" and "k" usage, is in Ireland, where there are many place names and surnames beginning with 'K". How to explain it.

While rarely mentioned in potted histories, Caesar apparently said that, while the Britons only spoke their own language, some could write in Greek. Possibly the same in Ireland, the Greeks being great sailors and mapmakers. There is also Kieran and Ciaran, of course. Also 'Kells" according to Bede is an alternative spelling of Cells.