The poem states that Avisa's house is found on the Western side of Albion's isle near where St Augustine pitched his monkly tent.
Historically speaking this is nonsensical .
Historians know that St Augustine entered England from the South East and never even visited the West . By including an historically inaccurate detail like this the author is indicating to us that he is using irony.
This means that although the author is stating West he is actually implying the East. And is really stating that Avisa's house is in the South- East of England near to where St Augustine made his first landing .
This is correct for Penelope Rich's house Leez Priory which is close to the coast and approx 20 miles from St Augustines first landing.