With the help of a school governor who worked in the food industry, he converted a shed into a storage room for dry foods such as pasta and rice, as well as soup. When the governor left, the local parish, All Saints, Kenton, stepped in to help.
But at every stage, O'Farrell said, some needy families felt unable to access the food because of "this huge issue of embarrassment." He believed that the problem could be solved if schools gave parents vouchers they could redeem at local supermarkets.
The Caritas Food Collective asked him to put his idea down in writing.
"I wrote it and I didn't think I was going to hear [any more] about it," he said. "Then all of a sudden we had lockdown and they wrote to me saying that they had put the plan into place. We were eligible for £500 worth of vouchers, which we've used. And we're now on our second lot of £500."
"I reckon we're supporting about 25 families at the moment. Every day now we have two or three families coming to use our food bank."
He described the plight of one family which was made homeless recently when the landlord increased their rent. They were rehoused in a neighboring borough. O'Farrell sent the mother vouchers and invited her to visit the school food bank. When she collected the food, she broke down in tears.
"It was just the first act of kindness she had received," he said. "She was so relieved because she was at the end of her tether. That was in week two or three of lockdown."
Asked what motivated him to find new ways to help families, O'Farrell said: "Christian values are very important to me and very important to the way we run the school. It's also my upbringing as well. I had to stand in the free school meals line with a different colored ticket to everyone else.
"But looking at these poor children, they are worse off. It's our duty as Catholics, as Christians, to do something about it."
O'Farrell underlined his gratitude to Caritas Westminster for its emergency food voucher scheme.
He said: "They've been brilliant. There's an email here from Anna [Gavurin] saying that on Friday we're getting a Hasbro toy delivery, because she's got a link with them. So some of our children will be going home with brand new toys on Friday, which is lovely."