JOHN Lewis has said the upheaval caused by the St James Centre upgrade in Edinburgh will cause “temporary pain” but its patience will be “paid back in spades” when the £850 million development is complete in 2020.

John Lewis is the only shop in the centre that will remain open during the works.

“It’ll be hugely exciting when it opens,” said Barry Blamire, managing director of the Edinburgh branch of John Lewis. “It causes temporary pain for us and the city, but we’ll be paid back in spades. It looks a fantastic development.”

That temporary pain was almost permanent after John Lewis threatened to pull out of the capital after TH Real Estate – in its capacity as both landlord and developer – included a third of John Lewis’ 150,000 sq ft sales space in a compulsory purchase order for the redevelopment.

After negotiations, John Lewis is losing just 30,000 sq ft, and when work is finished its floor space will have increased to 165,000 sq ft.

“We’re pleased with the outcome,” said Mr Blamire. “It was never our intention to pull out of Edinburgh; we genuinely did want to stay but we had to work with the landlord to find agreement for both parties. We’re really delighted that we’ve got the opportunity to trade through the works and continue to employ 700 people in Edinburgh.”

Mr Blamire admits he has no idea how the disruption of the works will affect takings.

“We’re heading into unknown territory,” he said. “We’re losing important entrances [in the mall] but we’re fortunate to have external frontage."

The store will be refurbishing the main entrance by the omni centre and creating a new entrance on Leith Street. John Lewis will also have an extended menswear department, a new consumer electronics department and sales space across six floor, as opposed to the current five. A new space on level five will also provide space for a café with views over the city.

“John Lewis will be the anchor shop in that new centre,” said Mr Blamire. “It’ll be hugely exciting and at the end of the project when we take the shop to 165,000sq ft we’ll be bringing in new concepts as we refurbish all seven floors.”

When complete, the controversial St James redevelopment – which includes at its centrepiece a five-star hotel designed to resemble a coil of golden ribbons – will contain 850,000sq ft of retail space including 85 shops and 30 food and drink outlets.

Council officials had urged Edinburgh City Council’s planning department to reject the design of the hotel, by London architect Jestico + Whiles, but plans were approved.

“We expect a certain level of disruption but John Lewis has an incredibly loyal base,” said Mr Blamire. “They’re relieved we’re staying open and I think the vast majority will take that detour [to the main entrance].”

He added that the integration of on and offline channels may also contribute to minimising sales reduction over the period.

The store is the ninth best performing in the estate, and while Mr Blamire could not reveals sales figures, he expected the store to benefit in the long term.

“We’re confident that the city and our sales will grow over time as we continue to invest in the store,” he added.