We really don't know when Heddon's St Andrew's Church was founded, but around 680 AD is the general consensus.
H.M. & J. Taylor in their monumental work 'Anglo-Saxon Architecture' put it in the period 600-800 AD).This fits with its dedication to St Andrew, which suggests that it may be contemporary with Hexham Abbey (674), Corbridge (676), Bywell St Andrew, and Newcastle St Andrew.
Bede, the Father of English History, has a couple of intriguing references in his 'History of the English Church and People', completed in 731.
In Bk.III, chapter 21, he records the baptism of one King Peada "by Bishop Finan .... at a well-known village belonging to the king (i.e. Oswy, king of Northumbria) known as 'Ad-murum', and, a little later King Sigbert was baptised "by Bishop Finan in the king's village of Ad-murum, so named because it stands close to the wall which the Roman's built to protect Britain, about twelve miles from the eastern coast". These incidents are both dated by scholars as 653 AD.
There can be little doubt that "the wall which the Roman's built ..." is Hadrian's Wall built about 122 AD, beside which Heddon village stands. Bede does not mention the name Heddon, but there is no record of this name (Hedun) in use earlier than 1175. 'Ad-murum' is translated 'At-Wall', not so different from 'On the Wall' (though in Latin our name is usually 'Hedon super murum').
Did Bede think that Hadrian's Wall began right on the coast (he twice tells of it running from sea to sea), and therefore assumed that the twelfth milecastle (at Heddon) was twelve miles from the coast?
On high ground, a splendid defensive position, Heddon as we know it would be an excellent site for 'the king's village'.
The site of Ad-murum has been located at various points from Newcastle in the east, to Walbottle and Heddon in the west. But the actual site of the King's village has never been found. The local historian, Cadwallader J. Bates, writing in 1885, argued strongly that Ad-murum with its royal villa was at Heddon.
If this is true, Heddon existed (probably under another name) in 653, and there the second Bishop of Lindisfarne, Finan, baptised the future kings of the Middle Angles and the East Saxons.
We usually date our church at 680, just after Hexham. If Ad-murum were identified with Heddon (and there is no evidence of it elsewhere) then almost certainly we could claim that we had a church here before 653.
Volume 1: Northumberland & Durham
Object Type: Finial cross or grave-marker
Measurements: H. 41.9 cm (16.25 in); W. 35.5 cm (14 in) D. 15.2 cm (6 in)
Stone: Medium-grained, massive yellow sandstone
Plate numbers in printed volume: Pl. 237.1341-3
Corpus volume reference: Vol 1 p. 241-242
The cross is carved in deep relief on a round block of stone which is joined to a rectangular base.
A (broad): Head type is E8 with the arms exaggeratedly tapered to meet a small flat roundel in the centre with a compass mark in its centre.
B, D and E (narrow sides and top): Plain.
C (broad): Carved with a Saint Andrew's cross in relief.
Discussion
Appendix A item (stones dating from Saxon-Norman overlap period or of uncertain date).
This type of head with tapering arms supported by a round centre seems typical of the overlap period. The narrow shank of the cross seems to indicate that it could have been set on the gable-end of a church, rather than having been used as a grave-marker.
Date: Eleventh century
References: Hodges 1923-4c, 279
Beneath the Norman window in the sanctuary is the head of a stone cross that was found beneath the vestry floor. It is now believed to be an Anglo-Saxon “preaching cross” around which people would gather when churches were few. The Celtic form of Christianity as evinced by St Aidan was much less hung up on the availability of sacred buildings than the Roman version championed by St Wilfred. Escomb in County Durham has a very different example behind its altar of what also might have been a preaching cross.
Heddon’s claim [to be the site of Bede's Ad Murum] however, is equally good. St Andrew’s church has Anglo-Saxon ‘long and short’ quoins at the south-east corner of the nave. And Milecastle 12 lies directly under Town Farm.
Was Heddon, then, the baptismal place of kings?