When the ancestors of the English came to Britain they spoke Old German which soon evolved into Old English . Little of their writings survives but what does was written in a Runic alphabet called the Futhorc after the first letters of their alphabet.
The Old English Futhorc originated from the Elder Futhark – the original runic alphabet developed and in use by the German tribes in the early centuries AD. The English tribes brought it to Britain but as the years went by their language and sounds altered. (Linguists call this the consonant shift and is why for example Ein Bett in German becomes a bed in English). With this cam ethe need for new letters to reflect those sounds.So the Old English Runes changed from the German with use.
Here (in modern alphabetical order) is the Runic alphabet:
The Runes were in use from the earliest days of the English settlement as demonstrated by a bone dug up dating to the 5th century with a single word “Rohain” meaning from a Roe written upon on it in Runes:
The eighth century British Museum Franks casket, which is believed to be from Northumbria, exhibits the runes as well as telling the tale of Wayland the Smithy of the gods and other sagas:
The Seax of Beagnoth was found in the river Thames in 1857 and dates to 9th century. Inscribed upon it is a complete 28 character set of the FUTHORC or old english runic alphabet. It also contains the name of the blades owner.:
The Runes began to be replaced by Latin characters in the 7th century with the coming of Christianity following the Augustine mission of 597 AD but were maintained in use in monasteries right through to the Norman conquest when they fell out of use even as a historical curiosity – probably all part of Norman suppression of English traditions.