Reptile takes 38 years to lay an egg (and it's hardly surprising, it took 12 years to get together with the father!) By Alexander Robertson

Breeders at a zoo are celebrating after finally convincing a rare lizard-like reptile to mate - and it's only taken 38 years.

Staff at Chester Zoo have been trying for four decades to get a female tuatara to breed, without any success.

However specialist keeper Isolde McGeorge, who has been caring for the species at the zoo since 1977, can proudly claim to be the first British midwife to the birth of a tuatara, which can live to the grand old age of 120 and are now solely found in New Zealand.

But it certainly wasn't an easy feat, with the particular pairing of a male called Pixie and a female named Mustard taking about 12 years to set up, ending with two eggs being produced.

The breeding of the reptile is notoriously hard, with each individual taking up to 20 years to reach sexual maturity and breeding conditions coming around at a rate of just once every four years.

The first tuatara hatchling finally emerged from its egg late last year after an incubation period of 238 days.

Ms McGeorge told The Independent: 'Immediately, I broke down in tears. I was completely overwhelmed by what we had achieved.

'Tuataras are notoriously difficult to breed, and it's probably fair to say that I know that better than most as it has taken me 38 years to get here.

'It's taken lots of hard work, lots of stressful moments and lots of tweaking of the conditions in which we keep the animals along the way – but it has all been very much worth it.'

The first youngster, named 'baby Isolde' after its enthusiastic keeper, was born in December, with Chester Zoo keeping tight-lipped about the birth until now.

The zoo is set to be the subject of a Channel 4 documentary series called The Secret Life of the Zoo, where staff will be filmed going about their work.

Although similar in appearance to other lizards, the tuatara actually belong to a different reptilian order called Rhynchocephalia.

After the female is inseminated, she lays her eggs in sand some distance from its home burrow.

After discovering both eggs, Ms McGeorge transported them and placed them in an incubator.