'Schools couldn't function without us'
While many teachers are still tucked up in bed, at 6am he is already on site to open up the building and supervise his team of cleaning staff.
After that, every hour is full: painting, filling in holes in the playground, unblocking drains, fitting new sinks and ploughing through sizeable piles of health and safety paperwork.
While the pupils are in, he keeps discipline around the site and says he provides a male role model - useful in a primary school with just one male teacher.
And even when his official hours are over, his day is often far from done. On top of his standard 7.5 hour day, there are the frequent 2am call-outs to fire alarms as well as incidents of vandalism or weather damage around the school.
"I love my job," says the Scot, whose hip replacement cut short his career as a carpet fitter. "There's a lot of freedom and I'm not behind a desk all day, but they don't pay me nearly enough."
For his years of dedication, he gets a salary of pound;14,500 before tax. His wife Denise, 57, works in a call centre so they can afford to pay their mortgage, which recently rose by pound;75 a month.
He said: "The problem is that being a caretaker was seen as a retirement job, something you spent the last 10 years of your working life doing - after doing a heavy job the rest of the time.
"It's not like that now. The job has grown and the responsibilities are greater, but some are paid as little as pound;9,000."
Mr Anderson is one of thousands of support staff working outside of the classroom to help the cogs of the British education system run smoothly. A recent government report estimated that there are 25,065 full-time equivalent site staff, and nearly 49,000 caterers, cleaners and cooks.
And that's not forgetting the 28,000 technicians and 42,000 people in pupil support roles, such as midday and cover supervisors.
But Unison says that one in five support staff earns less than pound;9,000 a year, and two-thirds earn less than pound;15,000.
Mr Anderson said: "Without support staff, schools would come to a standstill - they simply wouldn't be able to function.
"Many of us enjoy our jobs, but the pay offer we've had is ridiculous."