Prior to the October 2023 announcement, HS2 Ltd estimated that the total costs of Phase 1 would be £49 billion to £57 billion. The Department’s estimate was lower, at £45 billion to £54 billion but still above the funding envelope of £44.6 billion set in 2019. These estimates were all calculated 14 Qq 72–73 15 Qq 5, 37, 39 16 Qq 1, 6–7, 12 17 C&AG’s Report, Figure 8 18 Qq 6, 9, 13 19 Q 12 12 using 2019 prices.20 HS2 Ltd has continued to assess the cost of the programme and provided an even higher estimate to its Board in June 2024 of £54 billion to £66 billion, again still in 2019 prices. HS2 Ltd told us that this was based on new information and data from the supply chain. The Department reported that this estimate had been included in its six– monthly report to Parliament for the purposes of transparency. However, it was highly uncertain and subject to further assurance, and had not been approved by the HS2 Ltd Board or by the Department. Also, the estimate did not take into account work as part of resetting the programme and any private financing.21