A town planner by profession with both local authority and academic experience, her interest is at the strategic end of the planning spectrum, focusing on ensuring that housing has the right linkages into transport networks.

In 1997 Scottish Office minister Malcolm Chisholm appointed her to the National Transport Forum, and on being elected to the first Holyrood Parliament she found herself alongside party leader Donald Dewar as Minister for Planning, Transport and the Environment.

Sarah had no depute minister or special adviser, so she worked with civil servants, who were very talented but with an inheritance of mainly road-oriented projects. The new Government had a host of aspirations also for rail and bus, but the civil servants were clear that she was going to need additional funding. So along came consideration of road-tolling, congestion-charging and workplace-parking levies, all provided for in the first Transport Act. A visit to Norway revealed that tolls there were to raise money, not to tackle congestion and discourage car travel as had been her aim, and in the face of Opposition cries about highway robbery she was forced to retreat from tolling which had evoked a newspaper headline "On your Boyack" - while congestion-charging would be rejected by the voters of Edinburgh in a Council referendum.

With hindsight she had been trying to do too much too soon, and the clear lesson was that, especially in transport, you have to take the voters with you, with better alternatives and affordable choices available first. Major investment for rail was given the green light, and she created a bus priority fund and promoted free travel for over 60s. Local authorities could apply for funds to encourage walking and cycling. Priorities for the first budget were buses, ferries, potholes and key roads, and her Lib Dem coalition partners were supportive. The transport budget had overall doubled by the time she left the post.

Through the next two decades Sarah's views of transport were to be from an environmental perspective. In that time there has been a reduction in the cost of motoring and a substantial increase in bus and rail fares, with bus use well down as journey-times suffered from increasing congestion. Climate change has now grown into a full-blown Climate Emergency where there will have to be a focus on transport. Edinburgh has serious air quality issues which its City Mobility Plan seeks to address - and even in the pandemic the City Bypass and the M8 are jammed with cars.

Acton is needed globally now since the effects are visible everywhere, and the impact is disproportionately on lower-income groups. The Stonehaven derailment and repeated closures of the Rest and Be Thankful show the need to retrofit our infrastructure.

CoVid 19 has prompted heavy support to public transport networks in offsetting the loss of income, and there will be a need to make better arrangements taking account of people's new found taste for working from home.

Scotland's response will have to include accelerated action against climate change in anticipation of COP 26 while recognising the need to keep public transport going. The enthusiasm in lockdown for cycling has continued into the autumn, but to sustain this there will need to be dedicated cycle-routes and spaces. Cycling will also fare better if there are improved links into public transport, and for now it might be easier to keep on their bikes people who gave up on public transport because of the pandemic. Transport's share will have to be fought for since everywhere there will be competition for investment, with the NHS alone requiring vast sums for its recovery. Winning people back to public transport will require political commitment. The Scottish Government should not just fund ScotRail, but own it. Strong funding support and improvements in affordability and connectivity are vital so that buses and trains may join with walking and cycling in the fight against climate change.