The Prudential, originally named and funded by The Prudential Assurance Company Limited, was the prototype Ramsgate-class lifeboat built in 1925. It was one of the few lifeboats taken to Dunkirk by its own crew during the evacuation of 1940.

On Thursday, 30 May 1940, under the command of Coxswain Howard Knight, the Prudential set out equipped with gas masks and steel helmets. The lifeboat towed seven wherries loaded with water supplies for the troops awaiting evacuation on the beaches. Additionally, it towed the punt Carama, belonging to the lifeboat's second coxswain. Upon arrival, all boats discharged their water and other supplies to the soldiers ashore.

Due to the Prudential's deeper draft, it had to remain offshore while the naval ratings struggled to manage the wherries through breaking seas. Members of the lifeboat crew took over and successfully established communication with the officers in charge of the troops on land. Soldiers were ferried in batches of eight—the maximum capacity of the small boats—to the lifeboat, which then transported them to larger transport ships.

In total, the Prudential rescued approximately 2,800 men during the Dunkirk evacuation, carrying up to 160 soldiers at a time. On the return journey, the lifeboat assisted the 500-ton vessel SS Rian, whose engines were failing, by placing its engineer aboard to help bring the ship safely back to Ramsgate. The Prudential also towed a string of small craft filled with troops, including the punt Carama.

After enduring constant enemy attacks for forty hours, the crew returned to find the lifeboat had sustained major shrapnel damage and a hole in its bottom. For his exemplary service, Coxswain Howard Knight was awarded the Distinguished Service Medal (DSM).

The Prudential continued its service at Ramsgate for 28 years until 1953. During this period, it was credited with saving an additional 330 lives beyond those rescued at Dunkirk. In June 1953, the vessel served as the flagship of the Commodore, Lifeboat Division, at the Queen Elizabeth II Spithead Naval Review. Later that year, the lifeboat was sold out of service.

Renamed Trimilia in recognition of its rescue of over 3,000 persons in total, the vessel has been preserved in Suffolk since the early 1960s. In January 2011, Trimilia was relocated from Woodbridge to Ipswich. It is currently moored opposite the Old Customs House in the Haven Marina, where it attracted considerable attention during the 2018 commemorative event.