Part of the practice’s case crumbled earlier this year after it failed in court to establish that a contract existed when HTA was sacked.
Neither party would confirm the details of the deal. A spokesperson for the consortium said: “The agreement effectively covers the whole case.”
Last year, HTA’s solicitor issued a writ claiming £900,000 in unpaid invoices and £3.2m in future design work. But Judge Richard Seymour ruled the written communication between HTA and the consortium in November 1997 did not amount to a contract – which meant that HTA was unable to sue for a breach of it.