I was speaking to a gentleman from Newry today who, because we were discussing government policy and economic trends, told me the following story.
Isaac Corry, from Newry, was appointed Chancellor of Ireland in 1799 and one of his duties was to send out income tax forms - well, since a large proportion of the population could not read or write, he had the clever idea to introduce a tax on windows (and hence, light in homes) which proved to be highly unpopular (not just with the landed classes with the largest homes, but with the merchant class from which he sprang).
When the landowners received the bill, calculated on the size of windows, they disputed the amount and asked for windows to be re-measured. When the valuer went out the windows had, of course, shrunk. To allow more light into the home doors were cut in half - and that is the origin of the Irish Half-Door. This was also the origin of the saying - that 'he wouldn't give you daylight'.