The group, which has long been campaigning for the reinstatement of the Colne to Skipton rail link, is angry that over 90% of government spending on new infrastructure is still being pumped into already-well-connected communities of Southern England.
SELRAP chairman Peter Bryson said: "The spirit levels symbolise the current gross inequality in this government’s investment priorities.
"Therefore, despite its many promises, this government has repeatedly failed to actually deliver on investment in much-needed projects up in the North.
"For example, the long-overdue Skipton to Colne project – reopening just 12 miles of long-closed railway line – will regenerate many of the most-marginalised and economically-deprived communities in the UK. This includes all of the 'Red Wall' towns of Pendle, Burnley, Accrington, Shipley and Keighley.
"These spirit levels are a timely reminder that work on this much-needed line needs to start soon."