Why Are Most Angel Roofs in East Anglia? 
If Richard II’s preoccupation with the projection of royal power explains the first angel roof at Westminster, what is the reason for the subsequent huge concentration of angel roofs in East Anglian churches, and their sparse occurrence elsewhere in England and Wales?
There are over 140 surviving angel roofs in Britain. 59% of these are in Norfolk and Suffolk, a figure which increases to almost 84% for East Anglia as a whole (defined as Norfolk, Suffolk, Lincolnshire, Cambridgeshire and Huntingdonshire). Why are angel roofs so overwhelmingly an East Anglian phenomenon? 
It has been suggested that the huge bird-filled skies of the Eastern Counties prompted medieval East Anglians to adorn their church roofs with angels, as divine feathered intermediaries. This notion follows the art-historical theory of neuro-plasticity - the idea that the images and shapes that societies adopt in their art are subconsciously a product of environment and surrounding sensory influence. 
Alternatively, Sandy Heslop, Professor of Visual Arts at the University of East Anglia, has argued that what is probably the first angel roof in the region (at St Nicholas, King’s Lynn, likely to date from 1405-10) was built as a counterblast against the Lollard Heresy. 
Lollardy was a kind of proto-Reformation of the 1400s, and particularly strong in East Anglia. Its adherents rejected the authority of Church hierarchy, did not believe in transubstantiation, and deplored the role of images in worship, as an idolatrous distraction. Crucially, the first Lollard martyr, William Sawtrey, had been priest at St Margaret's Church in Kings Lynn and at Tilney in Norfolk. He was burnt at the stake in London in 1401, and amongst the (many) charges against him were that he had said he would “rather worship a man...than an angel of God”. 
Professor Heslop has suggested that the construction of the angel roof at King’s Lynn is a local repudiation of Sawtrey’s statement and a reassertion of Catholic orthodoxy through art. (A similar anti-Lollard motivation has been advanced for the much later prevalence of Seven Sacrament fonts in East Anglia by Professor Ann Nichols in her book Seeable Signs - The Iconography of the Seven Sacraments 1350-1544). 
I’m not really satisfied by either of these theories. 
Plenty of parts of the country have bird-filled skies, but not angel roofs; and the idea that the roof at King’s Lynn is motivated by a desire to repudiate one of the less prominent heresies voiced by William Sawtrey - at least four or five years after he had been executed in London - seems a little acrobatic. 
It is also not clear that St Nicholas Kings Lynn is the earliest angel roof in the region, if only because most of the other East Anglian roofs cannot be precisely dated. 
I think that it is useful to go back to basics and ask some simple questions: 
What elements were essential to enable the widespread construction of angel roofs in East Anglia, or anywhere else?
Which (if any) of these elements was peculiar to, or disproportionately present in, East Anglia compared with other regions? 
It seems to me that there are three preconditions for any ambitious medieval (or modern) construction project. 
The will or desire to do it, the money to pay for it, and the technical expertise to execute it. 

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