The importance of Cricklade as a station upon the upper Thames does not only proceed from its being the crossing place of a great road, it is also the point when the first important tributary stream, the Churn, joins the Thames.  Above this junction the Thames nowadays is hardly a stream; and even in the eighteenth century and earlier, before the digging of the Severn and Thames Canal, it must have depended on the weather whether there were any appreciable amount of water in the upper part or not.  It would probably be found, if records could be examined, that the mills at Somerford Keynes were not continually worked throughout the year, even when the supply of water had been left undiminished by modern engineering.  But when once the Churn (which, as we have seen, has a larger volume of water than the Thames) had fallen in at Cricklade the two formed a true river, with depth in it always sufficient to support a boat, and with a fairly strong stream, as also with a width sufficient for minor traffic; and it is after Cricklade that you get a succession of villages and churches dependent upon the river and standing close to its banks.

But though this piece of hydrography has its importance the chief meaning of Cricklade in history lay in the fact that it was the spot where this Ermine Street on its way from the south country to the Severn Valley got over the Thames, and the village connected with it was entrenched certainly in Roman and probably in pre-Roman times.  This entrenchment may still be traced.

The crossing of the Thames by the Icknield Way, unlike the crossing of the Ermine Street at Cricklade, presents a problem.

Cricklade, as we have seen, is a perfectly well-established site, and we owe our certitude upon the matter to the fact that the Romans had hardened and straightened what was probably an old British track.  But with the crossing of the Icknield Way no such complete certitude exists, for the Icknield Way was but a vague barbarian track, often tortuous in outline, confused by branching ways, and presenting all the features of a savage trail.  Doubtless that trail was used during the four hundred years of the high Roman civilisation as a country road, just as the similar trail, known as the “Pilgrims’ Way” from Winchester to Canterbury, was used in the same epoch.  There are plenty of Roman remains to be found along the track, and there is no doubt that all such roads, even when the State was not at the expense of hardening or straightening them, were in continual use before, as they were in continual use after, the presence of Roman government in this island; but the Icknield Way does not approach the river in a clear and unmistakable manner as would a Roman or a Romanised road.  It is on this account that the exact point of its crossing has been debated.