From a UK.gov website:

Scotland

Scotland’s next Census is in 2022. The ethnic groups will be:

Asian, Scottish Asian or British Asian
Pakistani, Scottish Pakistani or British Pakistani
Indian, Scottish Indian or British Indian
Bangladeshi, Scottish Bangladeshi or British Bangladeshi
Chinese, Scottish Chinese or British Chinese
Other

African, Scottish African or British African
Respondents write in their ethnic group

Caribbean or Black
Respondents write in their ethnic group

Mixed or multiple ethnic group
Respondents write in their ethnic group

White
Scottish
Other British
Irish
Polish
Gypsy or Traveller
Roma
Showman or Showwoman
Other

Other ethnic group
Arab, Scottish Arab or British Arab
Other (for example, Sikh, Jewish)

From the BBC in 2012:

Britain’s showmen: All the fun of the fair?
By Emma Kasprzak
BBC News

Published12 April 2012

As the travelling fair season begins, fairground workers from all over Britain are heading out on to the road. But while their presence is familiar, what do we really know about the people who work the fairs?

From the heated evictions at the Dale Farm traveller site in Essex to the new series of Channel 4’s controversial My Big Fat Gypsy Wedding, Britain’s travellers have been hitting the headlines.

But the travelling community has a third distinct subsection of which little is reported – showmen or fairground people.

Unlike Irish Travellers and Gypsies, showmen do not view themselves as an ethnic group but a cultural one united by the fairground industry.

… John Thurston, the chairman of the Norwich and Eastern Counties section of the Showmen’s Guild, is also frustrated by misconceptions people hold about the traditional view of the showman.

Mr Thurston, who is the fifth generation in his family to work on the travelling fairs, says: “We spend millions of pounds on equipment and yet the showmen are always portrayed as Gypsies.”

Another misconception he is keen to deny is concerns over fairground safety: “Our record on safety is second to none. If there’s an accident on the fairground it always makes headline news because it’s very rare. It’s a very safe industry to work in.” …

Mr Appleton says the public also do not understand the modern pressures the industry is facing as councils increasingly sell off sites used for fairs to developers who build housing on them.

“We’re a traditional people. We want to maintain these sites and this old way of life for our people and our future generations,” he says.

… But Ms Gunn, who runs a side stall and is the fourth generation in her family to work in the industry, believes despite the challenges it is traditional values that have kept the industry going.

“It’s a community. You know everyone from birth and you see the same people year after year. People help each other out.”

Prof Vanessa Toulmin combines her academic work with her funfair business – she was born into a showpeople family in Lancashire.

She is also the director of the National Fairground Archive, at the University of Sheffield, which she set up to try to alleviate misunderstandings the public have about showpeople.

“Part of my work with the archive was to make people understand we’re not an ethnic group but we are a cultural one,” she says. “We travel for business and it is a way of life.”

Prof Toulmin feels fairs have survived for as long as they have in part because of the local links built up by travelling.

“Local people have an identity that is linked to their region’s fair. They are a form of cheap entertainment which fulfil a community need.”

Their appeal also lies in their ability to span all ages.

She says: “Fairs are multi-generational, you go as a child with your parents, you go as a teenager with your first boyfriend or girlfriend and then when you get older you take your own children and grandchildren.”

From Wikipedia:

Showmen’s Guild of Great Britain
From Wikipedia, the free encyclopedia

The Showmen’s Guild of Great Britain exists to protect the interests of Travelling Showmen in Great Britain.

The Showmen’s Guild was founded as the United Kingdom Van Dwellers Protection Association in 1889 in Salford. The formation of the guild was the main turning point of Showmen identifying their lifestyle as a culture rather than an occupation, leading to the idea of Travelling Showmen being a cultural group.

Due to being an insular community, most marriages being within the community, their own language (called Paylaree), their own traditions and customs, and long lineages within the community, most Showmen identify as being part of their own unique cultural group. Due to travelling about, the average British Showman has a mix of English, Scottish, Welsh and/or Irish heritage. Lots have partial Romani (mainly Romanichal) and partial Irish Traveller heritage too, but despite this, Showmen developed as a group separately to both Irish Travellers and Romanichal Travellers, and their roots, cultures, traditions and diddicoy identity are separate and distinct.

In 1917, the Showmen’s Guild of Great Britain, as it became known, was recognised as the trade association for the travelling funfair business.

Also from Wikipedia:

Polari

Polari (from Italian parlare ‘to talk’) is a form of slang or cant used in Britain by some actors, circus and fairground showmen, professional wrestlers, merchant navy sailors, criminals, sex workers, and the gay subculture. There is some debate about its origins, but it can be traced back to at least the 19th century and possibly as far as the 16th century. There is a long-standing connection with Punch and Judy street puppet performers, who traditionally used Polari to converse.

Alternate spellings include Parlare, Parlary, Palare, Palarie, and Palari.

Description

Polari is a mixture of Romance (Italian or Mediterranean Lingua Franca), Romani, London slang, backslang, rhyming slang, sailor slang, and thieves’ cant. Later it expanded to contain words from the Yiddish language and from 1960s drug subculture slang. …

Usage
From the 19th century on, Polari was used in London fishmarkets, the theatre, fairgrounds, and circuses, hence the many borrowings from Romani. As many homosexual men worked in theatrical entertainment it was also used among the gay subculture, at a time when homosexual activity was illegal, to disguise homosexuals from hostile outsiders and undercover policemen. It was also used extensively in the British Merchant Navy, where many gay men joined ocean liners and cruise ships as waiters, stewards, and entertainers.

… The almost identical Parlyaree has been spoken in fairgrounds since at least the 17th century and continues to be used by show travellers in England and Scotland. As theatrical booths, circus acts, and menageries were once a common part of European fairs, it is likely that the roots of Polari/Parlyaree lie in the period before both theatre and circus became independent of the fairgrounds. The Parlyaree spoken on fairgrounds tends to borrow much more from Romani, as well as other languages and argots spoken by travelling people, such as Thieves’ cant and backslang.

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