You really aren't helping yourself VG - have you actually done any work to check the affordability of £135 to the average Sri Lankan in 1971? I suspect not.
£135 in 1971 would have been $329 (exchange rate was 2.4336). The average annual wage in Sri Lanka in 1971 was about $170 - so that flight would have cost nearly 2 years worth of gross wages for the average person.
To put this into context of the UK today - that would be a ticket costing over £50k.
Now I'm not doubting that you mum did afford that ticket - what I am doubting was that she could have afforded it if her background was like that of most Sri Lankans at the time. But given that the stories of your parents and grandparents (assuming these are true) seem littered with people off to medical school, deciding which other country (or even continent) to go to to study at university (including post-graduate), people off to private school, off to boarding school, someone "very high up in the British colonial business interests", I'd suggest that the people you describe didn't have a lived experience similar to the vast majority of people in Sri Lanka at the time, indeed not remotely similar to the vast majority of people in the UK at the time.
Medical school was free in India so you did not need to be wealthy to attend -you just had to get the grades to get in and then you had to study and pass your exams. Hence, despite my grandparents having very little savings and owning no property in India, my mother was able to qualify as a doctor. I believe that was the same situation in the UK - you didn't need to be wealthy and privileged to study medicine.
A medical qualification from India meant you could get a job as a doctor in Sri Lanka. You could also get a job as a doctor in the UK. The UK recognised medical qualifications from Commonwealth countries - I guess they realised the foreign doctors seemed to have the knowledge and experience to do the role and the British government seemed to be struggling to educate /train their local population to qualify as doctors.
Israel was offering funding to Sri Lankans to study in Israel so no my dad did not need to come from a wealthy background - he just had to apply, sit an exam, attend an interview and show aptitude and potential.
After he finished in Israel, Dad then got a job in an engineering firm in Sri Lanka. The British Council offered funding for dad to go to the UK for his Masters in Engineering - so again he did not need to be wealthy. So he took the offer but then the offer was revoked due to a change in Sri Lankan government policy. Hence, my mother needed to fly to the UK and start working as a doctor to fund him and they lived together in hospital accommodation.
But then you do seem to be accepting this point with your comment "They were educated professionals who started with very little money in the UK, but they had the privilege of their education and they did not find it that difficult to progress." This has been my point all along - advantage doesn't just mean having more money, it also relates to education and therefore earning potential and also to the skills and networks that typically go along with having high level education and professional skills which create opportunities that are completely beyond most people.
The issue has never been whether someone had £10 or £10k in their pocket, but the advantages they possess due to their (often multigenerational) background compared to the vast majority of people. As far as I can see Sunak has come from generations of advantage of that type - starting from a position near the top of the tree in India, relocation to East Africa and rapidly attained a position near the top of the tree, relocation to the UK and again rapidly attaining a position near the top of the tree. As I think I mentioned upthread advantage begets advantage.
I was under the impression from your posts that you thought Sunak's grandmother's immigrant experience in the UK was funded by her wealthy relatives. Your misguided focus on the cost of plane tickets, local salaries and your comparison of people who emigrate to the vast majority of people who don't and who stay put in their country of birth, seems to have totally misunderstood the immigrant experience. The whole point is that it takes a certain level of self-belief. skills, willingness to take a risk, sacrifice and hard work to emigrate - to leave behind what you know and your family and move to a more expensive, unknown country with very little funds and only a few family connections within a under-privileged, minority community to help you, but with the determination to use whatever skills you have to try to carve a new life for yourself and contribute to society and bring your family over.
Of course the average citizen of the country being left behind for pastures new does not make this move so it's irrelevant to compare the immigrant to the average person in their previous country of residence.
But what you should focus on is that if you were a minority in your original country of residence, it may often lead you to be brought up with the idea that you have to try harder, be better in order to succeed because you don't have the privilege of being in the majority. In these situations it is often drummed into you from a young age that as a a member of a minority community, your way to succeed was by focusing on excelling in education and getting professional qualifications that would lead to a well-paying in demand career, or a job with security, options to further your career and a pension e.g. in the civil service. People from similar backgrounds would have helped each other and shared useful knowledge, experiences and skills. This mind-set would have applied to the minority Indian community in Tanzania that Sunak's grandmother came from, and was the experience of my parents' ethnic minority community in Sri Lanka. This mindset is also passed to the children of immigrants to the UK, especially if their parents have learned this perspective from their own parents.
Your point all along seemed to give the impression that Sunak's grandmother came from a background of wealth and privilege compared to other immigrants who succeed in Britain or compared to local Brits. The point is that the average immigrant arriving in the UK in the 1960s and 1970s by plane was rarely rich or privileged compared to local UK residents, and yet through hard work, sacrifice, a focus on education and the aspiration to be able to use that education to eventually move into a job that would allow them to save, pay a deposit, afford a mortgage, some immigrants were able to make a comfortable life for themselves. The "privileged background" of Sunak's grandmother and my parents in comparison to British locals is that in the country they left, they were part of a discriminated against minority, and coming to the UK was just more of the same experience of discrimination, which meant they already had the skills and drive to push themselves to overcome that disadvantage, and they would network within their under-privileged community to figure out ways of compensating for the disadvantage of being a minority or find a way of overcoming that disadvantage.
