Johnston crashed at Greeba Castle during practice. He was brought to hospital by an AirMed helicopter to Noble’s Hospital on the island, before later being transferred to Liverpool for further treatment.

The 28-year-old was conscious, but the session was red-flagged following the spill off his Padgett’s Supersport Honda.

The accident could hardly have come at a less opportune time with the Maguiresbridge man just after having edged out James Hiller in the Superstock class, clocking the top speed of 128.896mph. Earlier in the day Johnston had also topped the Supersport qualifying at 123.369mph.

Johnston later revealed in a tweet that he had sustained a, “broken back, coccyx and finger,” in the incident.

Johnston was scheduled to ride a BMW in the Superbike and Superstock classes and was also down to compete for Ryan Farquhar’s KMR team in the Lightweight class for Supertwins.

Prior to the TT, Johnston had also had a spill in the Supersport race at the at the North West 200 injuring his back and neck. However that pain was offset by two podium finishes, a second place in the Supersport race being followed by a third spot in the first Superbike race in challenging conditions on the Saturday.

However this latest misfortune will doubtless be deeply frustrating for Johnston, has was finally coming back to the sort of blistering form he displayed before going off at the Spring Cup meeting in Scarborough last year.