And yet I have been disappointed in all of you this past week.

Like her older brother, Billie has cerebral palsy. She is a very outspoken and determined six-year-old girl - in fact I had better warn you all that she's expressed an interest in the nation's top job!

She cannot sit unassisted. She cannot walk unassisted. She cannot dress herself, tie her shoelaces or brush her teeth unassisted. But after a wonderful year at an amazing special school she has now settled in well at her brothers' mainstream school. She is popular in her class, is learning to read and write like her peers and has taken up chess and piano and is preparing for a role as a witch in an abridged version of Shakespeare's A Midsummer Night's Dream.

None of this would have been possible without the hours of therapy and the array of equipment we have organised for her. Services from our disability service provider are patchy - short bursts interspersed with months spent on waiting lists - so we supplement them with private therapy (average $75 a pop). We bought her an electric wheelchair when she was two ($17,000) and a power chair more recently, which allows her to stand up at the push of a button ($27,000). She received a bright pink manual wheelchair ($7000) for her sixth birthday. She has two types of walking frame ($550 and $3000) and a shower chair ($1500). Apart from one walking frame donated by the Lions Club, we paid for all this equipment via our ''disability debt'', also known as our mortgage, because either the state government would not fund the equipment (too young, too expensive, not strictly necessary) or funding would take unreasonably long.

And yet I do not mind one bit. As with many people with disability or their parents out there, I can do the maths over a person's lifetime. A correctly fitted wheelchair can be expensive, but compared with the personal and public costs of multiple surgeries in later years to correct dislocated hips or spinal scoliosis, investing in a chair really is a bargain.