Private investors could help stump up the cash needed to build Britain’s longest road tunnel in exchange for a share of the money generated from tolls. The Lower Thames Crossing (LTC) was one of string of major infrastructure projects thrown into doubt by the government’s spending review. The Chancellor of the Exchequer, Rachel Reeves, recently axed a string of schemes amid a £22billion “black hole” in accounts she says was left by the previous administration. It was speculated the £9billion road link, which would connect Kent and Essex via a new tunnel under the River Thames, near Gravesend, …