Work visa is not a problem for the right candidate.
however, unless the person is named on a grant, there are sponsorship conditions to meet:
- post being openly advertised for 28 days minimum;
- salary over New entrant: £31,400 or Experienced worker: £40,000 (for SOC codes 2311 Higher education
teaching professionals, from 31st March 2019);
- vigorous recruitment/selection process - sponsor has to give evidences why others on the shortlist were not selected.
It's almost impossible to get lectureship post for a fresh PhD graduate. In my university, they can perhaps get a short-term, i.e. <6 months, guaranteed hours contract (zero-hour type), with no possibility for T2 sponsorship. Any position longer than 6 months will require being openly advertised, unless it's a fully research grant funded position (appointee has to be named on grant).
Postdocs's salary is normally about 35k, which is enough for the initial T2 application (as new entrant, for less than 3 years' post) but any further appointments as TA/RA will have to meet 40k salary threshold - i have not heard of any RA has been offered this salary. Bear in mind the starting salary for a Lecturer (Grade 8） is normally only 40k, barely meeting UKVI's new policy.