The five-year-long refit of the UK Royal Navy’s Type 23 frigate HMS Iron Duke, which saw upgrades to warfare, communication, navigation, and other systems, cost over £100m for a vessel officially due to leave service in 2025.

In a written parliamentary response, published on 22 June, James Cartlidge, Minister for Defence Procurement, stated that the total anticipated project costs for HMS Iron Duke were “approximately £103m”, a figure which could see “slight adjustment” to “reflect ongoing negotiations” with the contractor Babcock.

The refit, which took place from 2018-2023, required 1.7m hours of labour in what was purportedly the largest overhaul of a Duke-class frigate to date. Broken down, the 1.7m hours of labour towards the refit works out to 340,000 hours annually.

Scheduled to be the fourth of the Type 23 frigates to be decommissioned, HMS Iron Duke has around 17,000 hours of service life remaining. This equates to approximately 100 hours of refit labour spent for every hour left as a commissioned vessel in the Royal Navy.

A Royal Navy spokesperson told Naval Technology that the fleet “continues to meet all operational requirements” at it transitions from the Type 23 frigates to the new Type 26 and Type 31 vessels.

“This modernisation involves sensible planning, such as the recent completion of HMS Iron Duke’s Life Extension (LIFEX) programme, to balance availability and deliver value for money,” the spokesperson said.

The departure of HMS Iron Duke in 2025 is to be preceded by HMS Lancaster in 2024 and will be the last of the general-purpose variants to be decommissioned.

In 2022 HMS Somerset completed a near-four-year service life-extension (LIFEX) programme, which required more than one million hours of refit work. The vessel was followed into the Frigate Support Centre ahead of completing LIFEX by HMS Iron Duke, with HMS Argyll and HMS Westminster due later that same year.

Although HMS Argyll had a planned out-of-service date (OSD) of 2023, the LIFEX is expected to see the vessel remain in service, potentially up to the 2027-2028 timeframe in order to maintain the already dwindling surface combatant numbers of the Royal Navy. HMS Westminster, the oldest of the anti-submarine warfare variants (fitted with Sonar Type 2087), is due to leave service in 2028.

However, the material state of some of the older Type 23 frigates is such that is it unknown whether all will be able to see out their scheduled service life. The upcoming reissue of the Defence Command Paper, expected to be published before UK Parliamentary recess, could offer some indication of the fate of the remaining Type 23 frigates.

The Royal Navy’s Type 23 frigates are due to be replaced by the five-strong Type 31 general purpose frigate, which recently was revealed to potentially have to undergo design changes even with the first two vessels already under construction, and eight new Type 26 frigates.

In financial comparison, the Type 31 frigates were budgeted to each cost approximately £250m, plus government-furnished equipment. However, manufacturer Babcock is in dispute with the UK Ministry of Defence over the profitability of the programme.

The larger Type 26 frigates, currently being manufactured by BAE Systems, are likely to cost around £1bn per vessel.