Also recorded as Hylman, Hylleman
This would at first sight seem to be an older form for spelling the name, based upon the OE hyll for a hill. However, it is by no means the oldest form, and it still persists to this day in a few places.
Internationally it is recorded in England, Sweden, Denmark, and the USA. It is recorded in the 1500s to 1679 in the UK, and as late as 1933 in the USA. It is found in Scandinavia in the 16th to 19th C.
In UK Censuses the name occurs only twice, once in the 1851 Census, and once in the 1911 Census. This strongly suggests this more recent use is either a clerical error, or a personal preference on the part of a Hillman stating their name at different censuses.
In the case of Gloucestershire, Hylman was a rare occurrence used in two entries for only one family in 1597, within records between the years 1589 and 1810 – a period of 221 years (see table below). In Hertfordshire in contrast, Hylman was recorded twice, again for one family between 1593 and 1600, during the period 1440-1630, suggesting a very brief sojourn in the area since they were all related christenings.
The following, taken from marriages in the Gloucester Parish Records between 1589 and 1810 illustrate the changes in recording the name over time in the same area[1].
There is almost complete overlap of the occurrence of the different spellings, with Hilman the first used, followed by Hylman, then Hillman. There were no occurrences of either Illman or Ilman.
Some examples of the occurrence of Hyl(l)man as a surname in England[2]:
1593 George Hylman, sonne of Robert, baptised 5 Feb at Rickmersworthe, Hertfordshire.
1600 Sara and Christian Hylman, daughters of Robert, baptised 6h March at Rickmersworthe, Hertfordshire.
In a trawl through Family Search (IGI)[3] over the period 1550-1679 the family name Hylman occurred 22 times in baptisms and marriages, in the counties of Sussex (5), Devon (3), Suffolk (1), Staffordshire (3), Gloucestershire (6), Hertfordshire (3), and Kent (1). Interestingly, there were a further 20 records of the name from other countries more recently – 1650-1857 – in Denmark (1), Germany (1), Sweden (4), and latterly – 1763-2006 – in the USA (12). These last in USA must be secondary distribution, but the other countries are almost certainly primary origins.
At Yatton Church, near Congresbury, in Somerset, church records indicate a succession of 15 terms of Church Wardens from the Hillman family from 1446 to after 1748. Their surnames were spelled variously Hullman, Hyllman, and Hylman, becoming Hillman only after 1700. Hyllman was used as the spelling between 1447 and 1539, but interspersed with other spellings (information from Allan Attwood & Elizabeth Cullen, 2005, pers. comm.).
Sources
[1] Phillimore, W.P.W. 1902. Gloucestershire parish registers. Marriages, Vol. VIII. http://www.archive.org/stream/gloucestershirep08phil/gloucestershirep08phil_djvu.txt
[2] The Herts Genealogist and Antiquary; http://www.archive.org/stream/hertsgenealogis00briggoog/hertsgenealogis00briggoog_djvu.txt
[3] Family Search (IGI). https://www.familysearch.org/search/collection/location/1986340?region=England