Robert de Oliveira, a business manager at Fairfax Community Newspapers, removed the child from the locked car after concerns were raised by some other office workers.

Mr de Oliveira said he tried to talk to the child, who was in his pyjamas, to see if he could unlock the car from inside.

When the child was unable to respond, Mr de Oliveira broke into the car with the help of a local truck driver using packing tape, a screw driver and an umbrella. Police arrived as they were unlocking the car.

"Luckily, it wasn't a hot day. It was a fairly cool day," Mr de Oliveira said.

"The child didn't seem to be distressed. It wasn't crying.

"We waited until the father arrived about an hour later."

Mr de Oliveira said the father appeared distressed and confused when he returned and appeared to regret what he had done.

Police said the 35-year-old father had parked in Norwest Business Park, a public car park on Lexington Drive at Bella Vista, about 10.45am on Wednesday.

The father returned at 11.45am where he was interviewed by police before being arrested and taken to Castle Hill police station.

He was charged with leaving a child in a motor vehicle and causing emotional distress. The charge carries a possible penalty of up to $22,000.

The man has been granted bail and is due to appear at Parramatta Local Court on August 5.

The federal government is proposing reforms to the childcare benefit system that could potentially restrict access to childcare.

Leanne Gibbs, chief executive officer for the Community Child Care Co-operative said the proposed reforms might result in an increase in similar incidents.

"These are the sorts of issues we will be running into, for sure," she said.

"There could be a horrendous back story.

"I think there are some real challenges for those in some [middle] income categories who are actively seeking work and not able to use regular childcare.

"The bigger story here is what we don't have, in NSW or Australia, a good high-quality education and care system that meets the needs of all children."

Prue Warrilow, national convener of Australian Community Children's Services said families were increasingly finding it difficult to get childcare because of a shortage of places, particularly for children aged under two.

Samantha Page, chief executive for Early Childhood Australia warned parents against leaving children in cars and urged them to seek occasional care or help from a friend or neighbour.

Members of the public have commented about the Bella Vista case on the NSW Police Facebook site and were split into two camps.

One group criticised the father as being irresponsible and the other took pity on what they speculated were desperate circumstances.

The comments included: "Hopefully this man can get some support for childcare and getting a job. Leaving a child in a car is awful and dangerous, but it sounds like an act of desperation."

One person said: "It's sad he doesn't have enough support that someone could have looked after the little boy while he went to the interview. It was wrong to leave the little boy but we don't know the whole story and it wasn't like the guy was in the pub..he was interviewing for a job so he can feed his family."

Another said: "Really there are people making excuses for this man and feeling pity for him. Seriously you don't leave a child in a car by itself not even for five minutes, what a stupid thing to do."

And another said: "No Excuses!!!!! It is NEVER alright to leave a small child in a car."

One said: "NO EXCUSE. Take the child with him to the interview. I did .... and got the job. I had no one to help me out. Do what you have to do to be a responsible parent."

One person offered the following caution: "Take care with the judgements folks, nothing is ever as it seems."