Labour has tried to draw a line under its history of disastrous military equipment spending programmes as it presented a report aimed at ensuring overruns never happen again.
Shadow defence minister Michael Dugher outlined the findings of a 10-month review into defence procurement which investigated how to cut delays and budget overspends in future deals.
Mr Dugher admitted that by holding its review Labour was "confronting the past" of contracts signed during its 13 years in power.
He said: "It is inescapable that the problems of defence procurement which plagued all governments continued on our watch. A future Labour government has got to do much better, which was why we wanted this review. We need big changes going forward."
Shadow defence secretary Jim Murphy claimed the 96-page report, which includes 37 recommendations, is "extensive, open and ambitious".
He said: "We have lived for far too long with a conspiracy of optimism. No more can we have a culture of frequently missed deadlines and estimates which are extended to the detriment of a delivery timetable. There must be more openness in the system and more ruthlessness when there are overruns.
"Being prepared to cancel projects when time and budget exceed 20% of their estimate is, therefore, an example of the recommendations to which we will give very serious consideration."
He said equipment was delayed too often because new technology offered improvements while the original order was still being built - delaying getting much-needed equipment to the frontline.
"The search for the exquisite can delay the deployment of the excellent," said Mr Murphy.