A River-class export to Poland

Why would the United Kingdom not sell River-class patrol vessels to Poland?

A sale is considered probable if Poland wanted the vessels and Britain had ships available or could build them for export.

The premise of a general British refusal is rejected. A sale is considered probable if Poland wanted the ships and Britain had hulls available. Building new vessels for export is another option. Britain's general willingness to export defence equipment is linked to the economic benefit.