Question: F. Duerr & Sons Ltd. is an independent British manufacturer of jam, marmalade, peanut butter and preserves, based in Wythenshawe, an area of what country?

Context articles: Peanut butter and jelly sandwich
Reese's Puffs
Justin's
Peanut butter
Joseph L. Rosefield
Jif (peanut butter)
Peanut butter test
Peanut butter, banana and bacon sandwich
Wythenshawe
F. Duerr &amp; Sons

A peanut butter and jelly sandwich, or PB&J, includes one or more layers of peanut butter and one or more layers of either jelly or jam on bread.
 Sometimes the sandwich is eaten open-faced or with one slice of bread folded over (effectively a "half sandwich").
 If the peanut butter is not spread on each slice of bread, the sandwich will become soggy if it is left too long to sit.
Reese's Puffs (formerly Reese's Peanut Butter Puffs) is a breakfast cereal manufactured by General Mills inspired by Reese's Peanut Butter Cups.
 At its launch in 1994, the cereal consisted of grain puffs flavored with chocolate and peanut butter.
 Later the format was revised to be a mixture of chocolate puffs and peanut butter puffs.
Justin's is an American brand of natural and organic nut butters and peanut butter cups.
 The Boulder-based company manufactures and markets jars and single-serve squeeze packs of nut butter, along with various kinds of organic peanut butter cups.
 Justin's peanut butter cups are USDA-certified organic and use Rainforest Alliance Certified cocoa.
 Both the peanut butter cups and nut butters are distributed through stores such as Whole Foods Market, Starbucks, and Target in the United States.
Peanut butter is a food paste or spread made from ground dry roasted peanuts.
 It often contains additional ingredients that modify the taste or texture, such as salt, sweeteners or emulsifiers. Peanut butter is popular in many countries.
 The United States is a leading exporter of peanut butter and itself consumes $800 million of peanut butter annually.
Joseph Louis Rosefield (18 Dec 1882 - 8 Nov 1958) was a California food businessman who invented modern, non-separating peanut butter in 1922 – 1923.
 His family business, the Rosefield Packing Company, was based in Alameda.
 His new production process was licensed to another company to make Peter Pan peanut butter in 1923.
 Rosefield Packing later marketed Skippy peanut butter in 1932; both brands are still sold today.
 It also introduced cylindrical "wide-mouth" jars for peanut butter in 1935.
 Peanut butter then became a vast food industry.
 Among other roles, Rosefield Packing provided emergency supplies of peanut butter to Hawaii during World War II.
 Rosefield's family sold Rosefield Packing and the Skippy brand to Best Foods in 1955.
Jif is an American brand of peanut butter made by The J.M. Smucker Company, which purchased the brand from Procter & Gamble in 2001.
 In 1955, Procter & Gamble bought Big Top peanut butter from William T. Young of Kentucky and, in the ensuing years, reformulated and rebranded it to compete with Skippy and Peter Pan.
 P. & G. named its product Jif, used oils other than peanut oil in its hydrogenation process, and sweetened the recipe, adding sugar and molasses.
 The original "Creamy" and "Crunchy" style Jif peanut butters both debuted in 1958.
 In 1974, "Extra Crunchy Jif" was introduced, followed in 1991 by "Simply Jif", a peanut butter variant with low sodium and less sugar than regular Jif.
 "Reduced Fat Jif" was introduced three years later in 1994.
 In 2014, "Jif Whips" was released as the first whipped peanut butter.
The peanut butter test is a diagnostic test which aims to detect Alzheimer's disease by measuring subjects' ability to smell peanut butter through each nostril.
 The test was originally reported in October 2013 by researchers from the University of Florida's McKnight Brain Institute, led by professor Kenneth Heilman, and involves measuring the ability of patients to smell peanut butter held close to their nose.
 The researchers concluded that patients with Alzheimer's were not able to smell the peanut butter as well through their left nostril as their right one.
 The study's lead author, graduate student Jennifer Stamps, got the idea for the study when, while studying under Professor Heilman, she noticed that none of his patients had been tested for their sense of smell.
 The idea of using peanut butter came to Stamps when she administered it to patients as part of a routine test of cranial nerve function.
 Their decision to use it was also motivated by the fact that it is a pure odorant (i.e. is only detected by the olfactory nerve), and that Heilman had told Stamps, "If you can come up with something quick and inexpensive, we can do it."
The peanut butter and banana sandwich, or peanut butter, banana and bacon sandwich, sometimes referred to as an Elvis sandwich or simply the Elvis, consists of toasted bread slices with peanut butter, sliced or mashed banana, and sometimes bacon.
 Honey is seen in some variations of the sandwich.
 The sandwich is frequently cooked in a pan or on a griddle.
 The recipe for the sandwich has been published in numerous cookbooks and newspaper stories.
 It is sold commercially in restaurants that specialize in peanut butter sandwiches, such as Peanut Butter & Co.
Wythenshawe ( ; pop.
 100,000) is an area of south Manchester, England.
F. Duerr & Sons Ltd. is an independent British manufacturer of jam, marmalade, peanut butter and preserves, based in Wythenshawe, Manchester, England.