> UK manufacturing employment fell especially steeply in the early 1980s during a recession triggered by a high exchange rate and high interest rates. The job losses during these years were documented in particular by Townsend (1983) and Fothergill and Guy (1991) and the process of deindustrialization more generally by Martin and Rowthorn (1986). The recession of the early 1990s added further major job losses (Gudgin, 1995). Thereafter, manufacturing output largely stagnated and manufacturing employment continued to slide even though the UK economy as a whole enjoyed 15 years of sustained economic growth.
What’s notable about New Labour was how manufacturing job losses continued even during a long period of sustained economic growth. Finance and knowledge sectors grew while manufacturing sectors declined.
Moreover, as to China specifically, the UK had little trade with China until 2000: https://www.bbc.com/news/business-53468925.amp
Likewise immigration really got turbocharged under New Labour: https://www.bbc.com/news/election-2015-32162123
When evaluating Blair's impact it's also important to look at regional shifts, with money and jobs becoming more and more concentrated around London at the expense of the periphery. You can argue about the causes of these shifts, but their existence is not in question.