Sir John Redwood is MP for Wokingham, and is a former Secretary of State for Wales.

In the early days of this government, I was asked by the Prime Minister how I ran the Policy Unit for Margaret Thatcher. I sent him a presentation on options for establishing a strategic policy vision and direction, and briefly described the way Number 10 worked when I was a young senior adviser there.

I urged him to keep the crucial manifesto headline promises of levelling up, getting Brexit done and not raising the main taxes as central drivers of policy. The overall aim must be the greater prosperity of the many by expanding the economy, making and growing more things at home and showing how Brexit freedoms could lead to more and better paid jobs and more businesses.

These aims could then fuel matters for Prime Ministerial leadership and decision, and delegated matters for the different departments of state. Each Cabinet Minister should be told what is expected of them and how their department fits in with the general strategy. That needs to be agreed on appointment.

Thatcher had a much smaller staff at Downing Street than more recent Prime Ministers. There were three of us, senior civil servants, who talked to her a lot, knew her mind and helped her fashion government speeches, decisions and interventions and chair committees to resolve disagreements. The Principal Private Secretary ran her diary, ensured two way communication with all government departments and Ministers, organised meetings, sent out letters of confirmation and instruction following individual or collective decision and filled her daily boxes with work.

As Head of the Policy Unit, I provided briefs on all the main meetings she attended or initiated, ensuring her views and the strategic vision of priorities and aims could be reflected in what she and the government did. I sent her proposals to start work streams in government to fulfil manifesto and other promises, and to remove or amend departmental proposals that did not fit with the strategy.

I ensured she had bilaterals with leading Cabinet members to avoid misunderstandings and to enable them to voice their worries or request more support when carrying through agreed major policies. The Head of the Press and media department was her voice to the third estate, reflecting her views and answering criticisms as need arose. She had a Political Secretary for Conservative events and party correspondence.

She was pleased with the results of this structure and said she thought it helped her achieve more. For example we helped her drive through the whole wider ownership policy of everyone an owner. The work embraced home purchase, more self employment, personal pension savings, employee share schemes and the privatisation programme.

The Social Security Secretary led a wide welfare review with emphasis on personal pensions and other savings, the Treasury led the share ownership and privatisation policy , the Employment Department worked on qualifications, training and simplifying self employment, and the local government and Environment department pursued the housing initiatives led by Right to buy.

The system worked for a variety of reasons. The most important was we three knew her mind or made sure we found out her view on a topic before telling the rest of Whitehall or the press. They knew when we spoke we spoke for the PM. It was relatively easy for other departments to work out the view in many cases, as there were some clear precepts and priorities that would always influence decisions.

The occasional much-debated big speech charted the future in important areas and led to work across relevant departments to see it through to implementation. The speech was always thoroughly prepared and shared in draft with those Ministers likely to be affected. We tried to ensure there was always consistency, clear direction and language that made it relevant to people’s lives. I tried to keep our work strategic, as the PM should not try to do the jobs of Whitehall departments for them. Number 10 is a leader and change maker, not a means of implementing policy.

The work of the PM and Ministers was not done once the policy was announced. Indeed that to me was the formal commencement of the actions, not the end result after a sometimes long and argumentative process to arrive at an answer.

It was important to supervise implementation and check that all was working as intended. It would be no good for the PM to set out what she wanted, for there to be no follow up work to make sure it happened. This might well be the job of named Ministers, but for the big items there also needed to be reports back to the centre. The twice weekly briefing sessions for PM Questions ensured departments had to keep the PM up to date with topical or fast changing items.

The task of writing the big speeches gave me plenty of time with the PM on a regular basis for what was in effect a series of long seminars and reviews of government policy and actions. We checked the speech drafts for accuracy and for relevance to the state of play the government needed to manage or alter.

Policy Unit members had access to the PM on their specialist topics as well as through me. They did not have any licence to instruct Ministers elsewhere in government, and were urged to be careful if Ministers asked for a steer. There was no Policy Unit view for outside consumption, only the Prime Minister’s view. The Policy Unit view was worked through and argued out in private and put to the PM who could run with it if she wished.

We adjusted the view in the light of her responses. I met the Special Advisers in other departments from time to time but did not regard it as any part of my job to guide or employ them. Our relations with Whitehall usually took place via a formal Private Secretary letter from Downing Street reflecting the PM’s view or informal guidance and arguments in official meetings preparatory to briefing Ministers or in our case the PM. I ensured the Policy Unit was at all times a working part of the civil service with career civil servants as well as directly recruited experts.

There is a modern relevance to all this. A Prime Minister needs a few advisers that he trusts who have sufficient delegated authority to get things done across Whitehall. It needs to be done in a constitutional way, respecting the fact that Cabinet members should be the main source of advice and information on their remits.

Where a senior adviser thinks a department and its Cabinet member are taking a wrong direction which can damage the overall government strategy and outturn that has to put privately to the PM and the two of them have then to agree how change will be achieved with minimum damage and preferably with no press knowledge. There can only be one government policy at any time, so where there is disagreement advisers need to help the senior politicians arrive at a suitable collective decision.

This should not always be a compromise as sometimes one course is right and the other full of danger, so a clear choice needs to be made. Any good Cabinet Committee required careful preparation to ensure Cabinet members could freely express reservations amid criticisms whilst keeping the integrity and coherence of the overall aims and vision. Where the dispute was the usual Treasury versus spending department one the PM was usually the decisive voice. Number 10 needed a strong negative capability to stop needless change or complexity, as well as a strong positive view of what government could and should do to improve the lives of the nation.