From frigates to patrol vessels: Which allied ships are heading to DSEI 2025?

Four warships from the UK, Belgium and Germany have sailed into London for this year's Defence and Security Equipment International (DSEI), one of the world's largest defence and security exhibitions.

Alongside them, the event will showcase live demonstrations of autonomous naval systems on the River Thames.

The Royal Navy will now be represented at DSEI by offshore patrol vessel HMS Mersey and Archer-class patrol vessel HMS Example.

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HMS Mersey is taking the place of Type 23 frigate HMS Iron Duke, which was initially expected to berth alongside the ExCeL exhibition centre.

Recent build-up of silt in that stretch of the Thames has reduced the depth of water, meaning larger ships like HMS Iron Duke, with a much deeper draught, risk grounding or having very little clearance under the keel when entering the dock.

By contrast, HMS Mersey is a smaller River-class patrol vessel with a shallower draught, making her better suited to the restricted waters.

A Royal Navy spokesperson has said that Iron Duke will remain on regular tasking.

HMS Mersey has been present at DSEI before, while HMS Example is a newcomer to the defence exhibition.

Based in Gateshead, HMS Example operates with a small core crew but plays a key role in training Officer Cadets and has regularly deployed on Nato exercises.

From Belgium, the coastal patrol vessel BNS Pollux is visiting the show.

She operates as part of the Belgian Coastguard, carrying out patrol, surveillance and search and rescue tasks in the country's Exclusive Economic Zone, and can also be deployed in wider European waters.

Representing Germany is FGS Sachsen, the lead ship of its Sachsen-class air defence frigates.

Commissioned in 2004, she is equipped with advanced radar and missile systems designed to protect naval groups from air and missile threats.

Sachsen has previously deployed with Nato's standing maritime groups and recently completed operational training in Plymouth.

Demonstrations of new maritime technology are scheduled to take place twice a day on the Thames opposite the Excel centre, where the biennial exhibition takes place.

Among the systems on display will be the UK's L3Harris Shadow Fox autonomous surface vessel, ACUA Ocean's USV Pioneer, and Latvia's VIC TEC unmanned craft, which can be fitted with torpedo launchers and air defence systems.

Rear Admiral (retired) Jon Pentreath, Senior Naval Advisor to DSEI, said the event would underline how allied cooperation and emerging technology are shaping modern naval warfare.

"The presence of these warships at DSEI UK reinforces the fundamental purpose of the show: promoting cooperation with our allies to counter common challenges and prepare our militaries for the threats of the future," he said.