Take off was delayed by technical problems. But forecasters were spot on when it came to where it landed.

Staff and pupils at Glebe House School, Hunstanton, sent a helium balloon almost into space.

Then they dived into the school minibus and gave chase, as its tracking device revealed its flightpath high above the clouds across Norfolk.

Bill Robinson, Glebe's head of computing, said the equipment offered aeronautics at pocket money prices, as he taped the camera, battery and GPS tracker into a polystyrene box.

Funded by the Raspberry Pi Foundation, the £40 latex balloon would soar to up to 100,000ft before bursting, allowing its equipment to return to earth by parachute.

'It's a great way to get the kids excited about science,' said Mr Robinson, adding Met Office wind speed forecasts suggested that the equipment would touch down near the A11 in the Old Buckenham area.

'It could land in the middle of the A11 and get crushed by a truck,' he said.

Lift off was delayed until tracking devices could lock on a signal from the baloon, code-named Eagle One.

'It's technical stuff, it happens to NASA,' shrugged Mr Robinson. 'At least the weather's nice.'

Inflated to around the size of a fridge, Eagle One strained at its leash before it was released, shooting into the heavens at an impressive rate of climb.

Instead of heading to the south-east, it soared over the school and out of sight over The Wash, before performing an aerial U-turn back onto its predicted course. Trackers revealed that after skirting Fakenham at high altitude, it flew across Dereham and passed to the south-west of Norwich, before landing in a field between Hapton and Low Tharston around three hours after launch.

As it lost height on its final approach, Eagle One was tracked by students at Glebe, who guided Mr Robinson and the school minibus towards it. Students are now studying data recorded by its sensors.