"These buildings which date back to the 19th century were not built to today's standards with important things like damp courses," he said.
"We needed to strip back the layers and make the building good for the next 100 years."
The whole project entailed putting in new drainage; restoring the windows (particularly the Georgian windows in the Justice Room); cutting out areas of dry rot and re-rendering the interior walls.
"We were able to find out more about the building due to the renovation," Paul said.
"We uncovered new doorways, the manure pit for the next door police stables and discovered new artefacts under the floorboards.
"A particularly poignant example is a couple of clay pipes which reminds me of the story of Mrs Ellis and Mrs Saunders who fought over a pipe with much hair pulling and name calling. They were brought in front of the bench in 1852."
"They love to uncover the stories behind the buildings and share them with our visitors."
The Society has developed a new exhibition for the building that reveals much about law and order in the early days of settlement, and includes artefacts from its important collection – the third most significant collection in WA.
"New research has been used to produce our 'Rogue's Gallery' telling tales of the gaol's various inmates," Celia said.
One of her favourites is Thomas Jackson who was charged with stealing grapes from Mr Devenish's garden in 1854.
"What's really interesting is that Thomas was sentenced to 12 months working in the Convict Depot for just stealing grapes.
"The court report does state that he was of 'very bad character'," she said.
The Prisoners Day Room will be full of items showing Guildford's colourful past and illustrating what a busy and vibrant place it was.
Guildford was a very important centre for many industries including brick making, flour milling, and wood merchants.
It was also the first place in Western Australia to have a built church on land given by Captain James Stirling, the first Governor.
Grapes for winemaking were grown in Guildford even before the Swan Valley.
"Our visitors find many of the artefacts surprising," Celia said.
"Did you know that leather horse slippers were used to stop the horses' hooves sinking in the sand?"
"We believe there is something for everyone with a visit to the Colonial Gaol.
"The tours also include our settler's cottage dating back to the 1860s and the story of Edward Taylor and his family, and a turn of last century wash house."
Celia said the Swan Guildford Historical Society are grateful to the City of Swan for their detailed work on the renovation and ongoing support to make sure that these important buildings continue to be enjoyed by all.
Admission to the museum is $5 for adults, $3 for children aged five to 15 and free to children under five years old.
School parties and groups can be taken by arrangement and group rates are available.
The museum is open from Tuesdays to Saturdays from 10am to 2pm, with the last admission at 1.30pm.
The museum is a 10 minute walk from Guildford Railway Station. It takes 20 minutes by train from Perth Central Station on the Midland Train Line with daytime trains running every 15 minutes.
Guildford is also served by the 36 bus from Elizabeth Quay to Midland.
Two hours free parking is allowed in the adjacent public car park.
The Guildford Colonial Gaol and Taylor's Cottage are in Meadow Street, Guildford.