Two years of planning and a large dose of imagination were also required to part Trishna and Krishna, who are expected to make a full recovery, medics at Melbourne’s Royal Children’s Hospital said.

‘We had Plan A, B, C and D ready — we even had a back-up team of microsurgeons to come and move muscle if necessary, to cover the gap,’ said plastic surgeon Tony Holmes.

‘But fortunately Plan A worked, which was rather lovely.’

Key to the operation were custom-made wedges, made from foam rubber available in stores throughout Australia, to keep the girls correctly positioned during the 32-hour operation.

‘Those were small but absolutely vital things for the procedure,’ said Andrew Greensmith, another plastic surgeon.

The team spent months growing extra skin on special tissue expanders implanted in the girls’ heads to cover the plate-sized holes in their skulls.

Meanwhile the neurosurgeons were guided by cutting-edge models which simulated the surgery in minute detail, down to the arrangement of blood vessels in the brain.

‘Every step of the way we’ve had to be innovative, we’ve had to rethink the way we do things,’ said neurosurgeon Wirginia Maixner.

The girls were anaesthetised on Sunday before the surgeons moved in the next day, cutting through their skulls before starting the ‘slow and tedious’ work of disconnecting the brains and blood vessels.

Some 24 hours later, after several pauses to ease blood pressure in the brains, the girls were apart for the first time.

‘We took the brakes off the beds in the operating theatre and literally, millimetre by millimetre, started to push the beds apart,’ Greensmith said.

‘We didn’t want to move quickly and tear anything.’

The plastic surgeons then closed the skulls using polythene plates and bits of spare bone, topped by the new skin grown over a period of months. But it was not until brain scans that the team knew the operation had been a success.

‘I think I did the chicken dance — a very short version of it — because that was when we actually could say we had done it,’ Maixner said.

‘To separate them, bring them through alive and in good condition — wow. That was the moment.’

On Thursday, less than two days after surgery, Trishna was awake and talking while Krishna was expected to be brought out of an induced coma later.

‘We’re all very chuffed,’ said Holmes.