The children all suffer from rare diseases that often display arthritis-like symptoms. Wayne's Kawasaki disease manifested itself in the form of high fevers and blood-shot eyes. Other illnesses bring symptoms such as joint pains and muscle aches.

Set up jointly by the non- profit Paediatric Rheumatism Association and Pacific Place for Operation Santa Claus - the annual charity event co-organised by the and RTHK - four children and their families were brought to Pacific Place's Santa House, where the children had a meet-and-greet session with their favourite bearded old man.

Santa Claus, who has shown up in Pacific Place over the last three years and declined to be identified, professed his love for Hong Kong and his job. "I love the people, it's a beautiful city," Santa said. "And I especially love the egg tarts."

He added: "When you have a passion and enjoy what you do, you'll never work a day in your life … There is a lot of sadness in this world, and there's no greater honour than being able to bring joy to people."

Yesi Kwee Su-fong, a marketing and promotions manager at Swire Properties, said the annual Santa House at Pacific Place began working with Operation Santa Claus last year.

"Helping Operation Santa is really meaningful since they fund small NGOs," said Kwee. "These are organisations without government aid or direct funding from the public. Supporting them gives us a sense of really helping and giving back to the community."

As a beneficiary of Operation Santa Claus this year, the Paediatric Rheumatism Association aims to provide material and spiritual aid to patients suffering from rheumatic diseases, as well as to educate the public on such diseases.

Rain, another member of the non-profit group, put on the brightest smile of all as he sat on Santa's lap. The boy had a particularly small stature for a nine-year-old, which his mother said was due to his rheumatic disease. "He isn't able to walk due to the severe pain in all his limbs," Mrs Siu said.

To this day Rain is still wheeled around in a trolley, but his mother said the association had helped her family a great deal since they joined five years ago. "We came to the group for a community and a chance to share experiences with other patients," she said. "They have really been a lot of help."

How you can give

• Donate online by credit card at osc.scmp.com/donate

• Donate at an ATM or any branch of HSBC (account number 502-676299-001 for SCMP Charities Ltd - Operation Santa Claus)

• You can donate with a cheque payable to "SCMP Charities Ltd - Operation Santa Claus" and mail it to: Operation Santa Claus, Morning Post Centre, 22 Dai Fat Street, Tai Po Industrial Estate, Tai Po, New Territories.

• Donations of HK$100 or more are tax-deductible. If you would like a tax receipt, please send the completed donation form and original bank receipt to the address above.

• Please call 26808159 or e-mail [email protected] with any inquiries, or visit us online at osc.scmp.com