John Lewis Partnership has unveiled radical changes, including running its department store and grocery arms as one business, which will no longer have separate managing directors.

The overhaul, resulting in the departure of Waitrose managing director Rob Collins, is designed to enable the partnership to ”break out of the cycle of declining returns that are affecting most established retailers”, said JLP chair Sir Charlie Mayfield.

As part of the retailer’s Future Partnership Plan, Waitrose and John Lewis will be managed by a single executive team reporting to the chair. There will no longer be divisional boards or separate managing directors.

John Lewis managing director Paula Nickolds will become executive director, brand, responsible for “the continued enhancement of the partnership’s brands and leading the development of customer experience and future innovations”.

Across the partnership, around 75 out of 225 head office management roles will be cut and there will be savings of £100m.

Mayfield said: “Our current structure has served us well in the past, enabling us to develop two of the UK’s most loved and trusted brands.

“In the last three years, we have delivered significant innovation and driven efficiency, maintaining market-leading service standards and growing customer numbers.

“However, the lesson of the last two years is that we need more innovation, faster decision making and bolder steps to align our operating model with our strategy. This is what the Future Partnership Plan is all about.

“Although there will be little or no disruption to our shops or websites in the near term, there will be considerable change in many other areas of the partnership as we bring the two businesses much closer together.

“These are necessary, and these changes will be difficult for some of our partners and we will implement them as carefully and sensitively as we can.

“We are confident, as a board, that when the programme is complete, the partnership will be better positioned to break out from the cycle of declining returns that are affecting most established retailers.

“We will be a more modern and more unified business with a leadership team and cost structure that will enable the business to thrive in the long term.”

The changes will also include the creation of a smaller partnership board.

Mayfield is handing over the reins as chair to Sharon White, who starts at the beginning of next year. Along with her, as of February 2020, the executive will comprise Nickolds, finance boss Patrick Lewis, people director Tracey Killen, operations director Andrew Murphy, customer service chief Berangere Michel and trading and strategy directors who are yet to be appointed.