Number of Looms in UK Year 1803 1820 1829 1833 1857 Looms 2400 14650 55500 100000 250000
Tell me how increasing your manufacturing base 104x in 50 years is possible without above average returns on capital in textiles? Were the British industrialists stupid? Did they just want to compete each other out of existence? Or perhaps they had a captive subjugated market where people were not even allowed to produce salt, let alone textiles.
Your argument that India would not have "kept up" is based on pure conjecture. Also, every respected economic historian writes that India would have been better off without colonialism. Transfer of technology doesn't have to coincide with being invaded. Eg. Japan.