Plymouth delivered just 96 affordable homes in 2025, a figure local officials have attributed squarely to the rising 'cost of building' rather than any shortage of planning consents or developer appetite. On the surface this looks like a parochial planning story about a single South West city. In reality, it is a symptom of a problem now afflicting nearly every local authority in England: the arithmetic of affordable housing delivery has broken down, and the gap between political ambition and commercial viability is widening fast.