Richard Leonard says his party is now committed to backing remain in its manifesto

Jeremy Corbyn has agreed Scottish Labour can campaign against Brexit even if a future Labour government brokers a fresh deal with the EU, Labour’s Scottish leader has said.

Richard Leonard said the Scottish party was now committed in its general election manifesto to campaigning for remain even if Corbyn won a better Brexit deal next year and put it to a referendum.

Speaking in Glasgow after he launched the party’s Scottish manifesto, Leonard hinted Corbyn had been reluctant to allow Scottish Labour to take a pro-remain stance. “I think he understands why we take that position, and I understand why he wants to negotiate a better deal from the EU over Brexit,” Leonard told reporters.

He said there was “no great division” over this, adding: “We’re reasonably relaxed. In the 1975 referendum [on the UK staying in the EEC] a decision was made which allowed members of even the Labour frontbench to go on different sides of the debate.”

Scottish Labour took a firmly pro-remain stance after it endured a humiliating defeat in the European parliament elections in May, recording 9.3% of the vote and failing to return an MEP from Scotland for the first time in its history.

Scotland voted by 62% to 38% in favour of remain in the 2016 referendum and the Scottish National party won three seats in the May elections and the Liberal Democrats a further seat on a firm pro-remain stance.

The Welsh Labour party has also announced it would back remain in a fresh EU referendum.

Leonard said he would expect all Scottish Labour MPs to campaign for remain in any fresh vote. Recent Westminster-focused opinion polls put Scottish Labour as low as 12%, and frequently a distant third behind the Scottish National party and Conservatives. Many party insiders believe it could lose many or nearly all of the seven seats it won in 2017.

In an effort to reverse that slump, Scottish Labour has unveiled multibillion-pound pledges to offer all school pupils free meals throughout the year, at an extra cost of about £231m, up to £2bn on a low-carbon Scotland-wide bus fleet, a £70bn infrastructure fund and £6bn on improving the country’s housing stock, alongside moves to reorganise the UK’s political structures on federal lines.

Despite Leonard winning the argument on the EU, the Scottish Labour manifesto includes several significant concessions to the UK party on both the timing of a Scottish independence referendum and on renewal of the Trident nuclear weapons system.

Leonard was embarrassed in August when John McDonnell, the shadow chancellor, said the party accepted a Labour government could not block a Scottish government request for the powers to hold a fresh independence vote. Until then Scottish party policy was to oppose one. After numerous missteps from Corbyn on its exact position, the UK and Scottish Labour manifestos now say a future Labour government would not accede to one in the first few years in power.

Leonard said his job was to prove that staying in the UK was in Scotland’s best interests; Labour would only agree to a fresh independence vote if there was “a clear and demonstrable mandate” for one with voters giving pro-independence parties a majority at Holyrood.

“With a radical Labour government we think the case for independence will be eroded, will be eclipsed,” he said. “I have to say to you, that battle will not be won and lost on the banks of the River Thames, it will be won and lost in Scotland.”

Under his predecessor Kezia Dugdale, Scottish Labour had voted to oppose renewal of Trident at its annual conference. Its new manifesto adopts the UK party’s policy supporting renewal, while putting the UK’s nuclear arsenal into multilateral weapons reduction talks. The SNP described this switch in policy as “an utter farce”.