The future of Thomas Heatherwick's proposed Garden Bridge in London is in jeopardy after a court ruling yesterday granted permission for a judicial review of the project.

A High Court judge ruled that Lambeth Council may have unlawfully granted planning permission for the new plant-covered Thames crossing and potentially ignored issues regarding funding.

The legal challenge was originally lodged in February by Lambeth resident Michael Ball, the former director of charity and community planning organisation Waterloo Community Development Group.

Under English law, an individual can request a judicial review to investigate the lawfulness of a decision made by a public body. In planning cases, this can result in the original permission being suspended or scrapped completely.

Ball claimed that the local council had failed to consider the impact the structure will have on surrounding historic buildings, and said it had not presented enough evidence regarding the funding for the bridge's maintenance over its proposed 125-year lifespan.

An initial ruling recognised the first of these issues but not the second, but this has now been overruled by a second judge who has granted permission for a judicial review investigating both claims.

The court order could present a significant blow to the £175 million project, which was due to start on site later this year to avoid clashing with construction of the proposed Thames Tideway Tunnel – a major new sewer set to get underway in 2017.

The Garden Bridge Trust – the non-profit organisation behind the project– dismissed the allegations and claimed it had a firm financial strategy to manage the upkeep of the 367-metre-long bridge, which if built would span the river between the South Bank and Temple.

"We have a clear business plan in place to fund the construction of the Garden Bridge and the estimated £3.5 million per annum needed for ongoing maintenance and operations," said spokesperson Harry Zelenka Martin.

"We will use a mixed model approach to secure the funds including individual and cooperate membership programmes, a small number of sponsorship opportunities and events, as well as some carefully selected commercial opportunities.​"

"​​In the meantime we ar​​e working closely with the London Borough of Lambeth to discuss the next steps following the decision and continue to work with stakeholders and local communities with the intention to begin on site early next year,"​ he added.

Zelenka Martin also rebuffed claims that the bridge will destroy views across the river, and said the group had carried out a full assessment of the structure's visual impact and its relationship to St Paul's Cathedral.

"The Garden Bridge has been designed to minimise the impact on protected views in this location," he said. "It is acknowledged that some views to St Paul's from Waterloo Bridge and the South Bank would be lost."

"The Garden Bridge allows existing views to be framed by new trees and be enhanced by this new iconic structure in the River Thames," he added. "New views from the bridge itself would be unique, featuring views of the iconic London riverscape and skyline from a richly planted garden setting."

The court hearing is scheduled to take place in June. In the meantime, Ball is raising money for his appeal via a crowdfunding website.