The train trip from Ryde Pier Head to Shanklin on the Isle of Wight in carriages built 80 years ago for the small tunnels of certain London Underground lines could never be described as a smooth one.

Passengers are jolted up and down and, if they are not used to the ride, are thrown around when they rise gingerly from their seats. It is a lurching, rolling experience – but locals and visitors relish it.

“It’s great, isn’t it?” said 67-year-old William Bremner, who had caught the train after arriving on the island by ferry and was off to visit his sister. “I like the rhythm of these trains. This trip livens up my life.”

However, the days of the 1938 Class 483 EMUs (electric multiple units) – the oldest train fleet on the UK’s national network – are numbered. From summer 2020, replacement trains will be tested on the eight-and-a-half-mile stretch of line and the buffers will draw into sight for the current stock.

Almost all the passengers the Guardian spoke to during a trip on the train expressed sadness at the prospect. Isle of Wight residents Ash and Sammy Butler were travelling with their son Codie, two, all of them Isle of Wight residents. “I love the quirkiness of it,” said Ash. “You can tell the locals from the visitors straight away. The locals know how to sway with the train. Visitors get bounced all over the place. It’s a bit like being on a boat.”

Facebook Twitter Pinterest Ash and Sammy Butler and their son Codie onboard one of the old trains. Photograph: Simon Czapp/Solent News & Photo Agency/Solent News

The trains may rattle but they are also lovely. The carriages feature wooden and brass trim. The livery is a deep red.

Kathleen Neil and her friend Barbara Snelling manoeuvred on to the train on their mobility scooters, helped by an attentive guard. “It is rickety but that’s the charm of it,” said Neil, who has being riding on the trains for almost 40 years. “We roll on and off all the time to go shopping and meet friends. We love it.”

The history of former tube trains on the Isle of Wight stretches back more than half a century. Space is at a premium on the Island line, and the size and shape of converted tube trains made them suitable.

The first of these ran on 20 March 1967 along the island’s newly electrified lines. In 1978 the Guardian reported that the trains gave the Isle of Wight the feel of an Ealing comedy.

The current generation of 1938 tube trains began operating in the summer of 1989. There have been hitches, including a runaway train, and for a time the trains were painted in undignified “dinosaur” patterns. Now time has caught up with them and they have become rather more unreliable.

Facebook Twitter Pinterest Barbara Snelling (left) and Kathleen Neil disembarking the train. Photograph: Simon Czapp/Solent News & Photo Agency/Solent News

Richard C Long, who has written a book, Ryde Rail, on the history of tube trains on the island, said it was sad to see the 1938 trains go but the move was inevitable. “They have a unique quality about them. Many people like their art deco look,” he said.

The clattering was not the fault of the trains, he added. “The lurching about is not due to the trains but the track.”

A £26m investment will bring new trains, tracks and infrastructure. The link with London Underground will continue. Vivarail is supplying four EMUs converted from former District Line trains and dating from the late 1970s and early 80s. They are promised to be smoother and will even have wifi.

“It will be sad to say goodbye to these carriages,” said Paige Mills, 25. “I’ve ridden on these trains since I was knee high to a grasshopper.” Now she travels on them with her eight-month-old, Louie. “One of the great things about them is that they rock my baby to sleep. I wonder if the new ones will do that?”

• This article was amended on 3 January 2020 to clarify that the incoming Isle of Wight trains are converted London Underground stock (as opposed to the outgoing “tube” stock, built for certain small-tunnel lines on the London system).