450+k Chinese in the UK, mobility is easy and they are widespread. Not difficult for an Anglicised/Anglo Chinese SP to make her way to any major city and work if inclined to and to exclude Chinese punters just like other ethnicities do.
Latest unemployment demos indicate c15000 unemployed "Chinese" so not exactly a large number of women, even if they were all female, for the percentage that might turn to prostituition. The overwhelming majority of Chinese women I've encountered in parlours or in flats and others have as escorts have been immigrants, here (il)legally. Once the family establishes itself here then, as with other South and East Asians there is huge pressure for aspiration by the next (and subsequent) generations to aspire to "professional" and "respected" careers or to roll into the family business of catering, retail, import/export and perhaps increasingly nail salons! Filipino competition notwithstanding.
Given the proportion of native Brit Causasians trading as SPs, if the same percentages are applied for naturalised Chinese (or any other ethnicity) that's not alot of SPs. I'm not aware of there being any increased propensity for different Asian ethnicities to become SPs, especially once they're naturalised, even if the home culture is more tolerant of sex-work e.g. Thais or Filipinos. My slightly more limited exposure (fnah!) to Thais has found many stories of ladies here wisely sending money home to their familes and children back in Thailand or else seeing their children here into regular employment. Admittedly only a few have admitted to having daughters here and most of those won't be legal for another decade.
Sadly never had a cheeky, saucy Thai or Chinese matron suggest I meet her lovely sexy daughter instead for a good servicing.
Happy to have other punters attest to these nth gen SP unicorns existing.