The core rulebook lists Bishop Roger as the Bishop of Salisbury, but is he actually a bishop? The Books of Uther and the Warlord state that there are only ten Roman Christian bishops and Roger is not listed among them. And Salisbury is noted as part of the Bishopric of Silchester under Baron Metellus. Equally, Roger is not listed among the British Christian Abbots.

So, is Roger a Bishop or is this simply a mistake in the core rulebook? Or, is he Baron Metellus' predecessor? Or, a British Christian Abbot-Bishop?

And if he is not a Bishop, who is responsible for Salisbury Cathedral?

I'll let Greg answer this, but...

One thing to keep in mind is that KAP 5.1 predates BotW by like a decade. A lot has changed during that time.

However, given that Roderick is British Christian, it would make sense that he would be a British Christian Abbot-Bishop of Salisbury. In GPC p. 29 it says that the Salisbury Cathedral is overseen by a bishop of the British Church. One remaining contradiction is that the KAP 5.1 write-up has him controlling Amesbury's lands, too, whereas BotW (and BoU) has Abbot(-bishop) Dilwyn. But that is easily ignored, as is the presence of Abbot Rhain of the Russet Monks in the Rock.

The core rulebook lists Bishop Roger as the Bishop of Salisbury, but is he actually a bishop? The Books of Uther and the Warlord state that there are only ten Roman Christian bishops and Roger is not listed among them. And Salisbury is noted as part of the Bishopric of Silchester under Baron Metellus. Equally, Roger is not listed among the British Christian Abbots.

So, is Roger a Bishop or is this simply a mistake in the core rulebook? Or, is he Baron Metellus' predecessor? Or, a British Christian Abbot-Bishop?

And if he is not a Bishop, who is responsible for Salisbury Cathedral?

It is an error to list him as a bishop so early.
He is promoted later, sometime in the middle Phase, and makes the cathedral.
Sarum isn't even classed as a city in the earliest stages, not even a market town

Thanks Morien and Greg. That clears up my confusion over the Bishop. So, the Sarum 485 map from GPC shouldn't actually show a cathedral, I take it? It should still be the Church of the Blessed Virgin Mary, right?

According to the Word of Greg, correct. :)