The extent of the devastation at Cosmo Books stunned not only owner, Robert Downie, but also firefighters who managed to stop Wednesday's blaze spreading to other units on the industrial estate.
Mr Downie has vowed to rebuild the business, saying he had received messages of support and offers of help from across the world.
"Cosmo Books was entirely destroyed in a fire, from an incident at a neighbouring unit behind us," he said.
"Our entire stock of about 170,000 titles has been lost, and nothing can be salvaged from the destruction. We are therefore closed for business for the foreseeable future."
He said the knowledge that the fire had been started deliberately had hurt him and made him angry.
"Whatever the reason the knowledge that someone's very deliberate actions has led to the destruction of 170,000 titles - maybe 85 per cent of them from the 18th and 19th century or earlier is awful. It is the banality of it."
The alarm was raised about 12.30am on Wednesday. Firefighters arrived to find flames shooting from the roof.
It started in an adjoining unit to Cosmo Books but spread along the roof space. The fire burned through ceiling panels and onto Mr Downie's huge collection of books, built up over 25 years.
His catalogue attracts buyers from as far afield as America and New Zealand.
He was first alerted when getting ready to drive to the business park for work on Wednesday.
"A friend said there was a fire, the roads were closed and I might not be able to get in. As soon as I got there and saw how big the fire was I knew I would be looking at total destruction."
The entire stock - apart from about 150 books stored in the office - was completely destroyed by fire or water damage.
But Mr Downie has nothing but praise for the firefighters who worked through the night in difficult conditions.
"Once the fire broke through the roof space into my unit there was nothing they could do for me. But their remarkable hard work managed to save my neighbours' businesses and for that I am very grateful."
"The community has been so supportive. I have been offered space where I can set up an office while we look at how we can rebuild the business. I am too young to retire and the messages of support have come from as far away as New Zealand."
"Books are unlike anything else, we can not simply get new stock on a pallet or a lorry. We had built up between 1500 and 1600 Acts of Parliament for instance, now all destroyed.
"I was involved in my parents' book shop from the day I left school at 16 and you can not help but have an affinity with them. We will rebuild."