‘Buried in Woollen’ What an odd sentence!
So I thought, whilst indexing very old, late 17th century documents for the church of Jesus Christ of Latter Day Saints. I was indexing English burials and once started on the list, nearly every name was also accompanied by an affidavit stating that the person was ‘Buried in Woollen’
It seemed to be very important to state this on the burial affidavits. I wondered about this unusual practice and decided to find out.
The museum in Hungerford, Berkshire England shows an affidavit similar to the one I was indexing.
I have written it out as it states on the affidavit. Note that the letter ‘F” reads as an ‘S” in Old English.
Name of deceased……….of the Parifh of………….maketh Oath that…………………of the Parifh of lately deceased, was not put in, wrapt or wound up, or buried in any Shirt, Shift Sheet or Shroud made or mingled with Flax, Hemp, Silk, Hair God or Silver, or other than what is made of Sheeps. Wooll only nor in any Coffin lined or face with any Cloth, Stuff, or any other things whatforever made or mingled with Flax, Hemp, Silk, Hair, Godld or Silver or any other Material contrary to the late Act of Parliament for ‘Burying in Woollen, but Sheeps Wooll only. Dated the…………..Day of….. in the………….Year of the Reign of our Sovereign By the Grace of God, of Great Britain, France and Ireland, Defender of the Faith, etc. And in the Year of our Lord God 17……..Seated and Subfcribed by us who were prefent and Witnesses to the Swearing of the above faid Affidavit.
I do hereby Certify That the Day and Year abovefaid, the faid Affidavit as is above mention’d according to the faid late act Act of Parliament intituled, An Act for Burying in Woollen. Witnefs my Hand the Day and Year above-written.
(Printed for P. Barret Stationer, over-againsf Chancery-Land in Fleetfreet). 
Only those with the plague or who were destitute escaped this law. So much for the rules of burying in woollen. But why?
Between 1665 and the turn of the century, wool became a national symbol of importance in England, but new materials and foreign imports were coming into the country and the industry was under threat as linen, silk, and satin were readily available and the need for woollen dropped away. Workers who specialised in silks, satins, and linens flocked into the country and the need for wool waned.
Most of the wealthy depended on wool for their lifestyles, and some of these wealthy sat in Parliament, Members whose constituencies depended on the woollen industry, and was an essential part of their fortunes. These Members depended on rents paid by tenants who worked in the woollen trade, and so they changed the laws.
Most people were buried in linen shrouds. It was the custom and older than Christianity itself, but it also benefited England’s greatest rival across the Channel, the French, who provided most of all England’s linen. So, to stymie the French and preserve the woollen trade in England, Parliament developed the law of burying in Woollen only.
The first Act was passed in 1666 and the second, and rather more famous, in 1678 repealing the first Its aims were “for the lessening the importation of linen from beyond the seas, and the encouragement of the woollen and paper manufacturer of the kingdom.” 
Below is an extract from the Act.
For more of the legislation see The Justice of the Peace, and Parish Officer, Volume 5, 1814 on Google Books
The Act was not without its protesters as a more wealthy set wanted to be buried in their finery, not woollen.
“At first nothing could be more shocking,” wrote philosopher Bernard Mandeville, “to Thousands of People than that they were to be Buried in Woollen.”
“Our Savior was buried in Linnen,” protested Edward Waller, the representative for Hastings. “‘Tis a thing against the Customs of Nations and I am against it.”
Henry Coventry, Secretary of State for the Southern Department, was harsher, suggesting that “men of the Romish Religion” (Romish belonging or related to, Rome as Catholics) prefer woollen burials to linen. “I fear this Bill may taste of Popery,” he sneered.
Citizens were fined five pounds if they did not obey the law but many would pay the fine rather than be ‘seen dead in wool’ In 1678 this was an enormous sum of money about $1,000 in today’s money. 
The Act was repealed in 1814, although long before then it had been largely ignored.
 Eric W. Nye, Pounds Sterling to Dollars: Historical Conversion of Currency, accessed Monday, March 25, 2019, http://www.uwyo.edu/numimage/currency.htm.