Lord Andrew Hardie oversaw the Edinburgh trams inquiry. Picture: Lisa Ferguson

The main opposition party at City Chambers said it is “fundamentally opposed” to the proposals to take Edinburgh’s tramline down Leith Walk to Newhaven before the inquiry results have been published, in order for lessons to be learnt.

The council will decide whether to go ahead with the tram extension in December, but it remains unclear when Lord Hardie will report back on the failures of the first phase of the tramline.

The tramline was opened years late and cost £776 million for a shortened route – more than double the original budget. The cost of the tram inquiry itself has now hit the £9m mark.

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Conservative Cllr Andrew Johnston asked Leader of the Council, Cllr Adam McVey, for clarity on the administration’s tram intentions.

He said: “Why is he content to green-light the £165m project this Christmas, regardless of what Hardie reports?”

Cllr McVey said lessons would be learnt as the process moves forward.

He said: “We’re still going through a process to finalise designs and finalise options and make sure the business case is as robust as it has been throughout the process where we decide whether we want to go ahead with it or not.

“If Lord Hardie responds within that time-scale, then we will address it within the report that goes later in the year. If he hasn’t reported by that time, we will respond in a different way.

“Until he comes back with something, I’m not going to pre-judge what our response will be to that. What I would reiterate again is I expect and the people of Edinburgh expect this inquiry to come to an end and come to an end fast.”

He added: “Lessons learned from the publication of the inquiry, as well as experience gained through the delivery of the original tramline, will be invaluable as we work towards the expansion of the city’s tramline.”

Cllr Johnston has now called for the council to “slow down and wait for whatever advice comes out”.

He added: “I think there’s dangerous signs of complacency from the council leader, given it was a disaster last time. It was one of the biggest shambles that has happened in Edinburgh over the last few years.

“We have to wait to see what Lord Hardie concludes, stop being so complacent about a huge decision and use a bit of logic. In principle I’m not against it, but I would be fundamentally opposed to doing this before we have the results of the inquiry.”

The Liberal Democrats have also demanded the tram inquiry findings are revealed before any extension is agreed.

Cllr Kevin Lang said: “The recommendations arising from the tram inquiry must be known and incorporated into the project before final decisions are taken before any construction contracts are agreed. It is not only the right thing to do, it is what the people of this city would expect.”