Within two years the biggest shakeup in rail services for half a century will affect Medway’s travellers.

New stations, longer platforms, and the fastest commuters trains in Britain will be operating on the old North Kent Line.

Yet if it hadn’t been for sailing barges we wouldn’t have the rail line to St Pancras.

The 140mph (225kph) Class 395s will run from all the mainline stations in Medway from the end of next year, calling at Gravesend, Ebbsfleet, the Olympic station at Stratford and St Pancras.

It is unlikely there would have been a rail line if the navvies had not picked and hacked their way under the North Downs between Higham and Strood 200 years ago.

They gouged out a huge tunnel through which sailing barges could get from the Thames to Medway with ammunition and explosives.

It was part of the defences to keep Napoleon’s forces out of the capital if he had invaded England.

Chatham was the home of Nelson’s fleet, and the Thames estuary was dangerous waters to sail when gunships were hunting you.

But their work was in vain.

By the time the two-mile tunnel had been hewn by hand, and boats were able to pass through, Napoleon was a prisoner, the threat had gone, and Robert Stephenson was showing that something called a train could do an astonishing 29 mph. That compared pretty favourably with the walking pace of a barge.

The canal through the tunnel was filled, and on February 10, 1845 the first train ran through it between Gravesend and Strood.

Four years later South Eastern Railway(SER) began running trains from London Bridge to Medway via Lewisham and Woolwich, and in 1856 the line was extended along the Medway Valley to Maidstone.

Train firms declare war

The next development came when the East Kent Railway opened up the line from Faversham to Chatham in January 1858.

They relied on a horse bus for a few weeks until a line was forged to Strood for getting passengers to the capital.

At that point the East Kent (later renamed the London Chatham and Dover Railway, or LCDR) put its carriages on the back of the SER to give passengers a through journey to London.

But commercial war broke out in the 1860s when the LCDR opened up its own London route, via Bromley on the present day Victoria line.

The East Kent lost many passengers, but eventually built a line to what is now Rochester Riverside, and called its terminal Chatham Central. It closed after 20 years in 1911, by when the two companies had come under one management, the South Eastern and Chatham Railway.

In 1930 the first electric trains ran to Gravesend, but by 1939 the lines had extended to Gillingham and Maidstone.

It was another 20 years, however, before the rest of the line to the Kent Coast was electrified.

The future

Ironically, the modern day operator, Southeastern, is planning to drop Higham - the oldest station on the line, dating from 1845 - from its HST timetable.

The present Strood station was built in 1973, around the time that through trains were run to North Kent and Maidstone, rather than dividing at the station. Now they forecast that within five years, the station will see a 61 per cent increase in passengers.

One of the curious features of the old competitive days still remains. That’s the bridges which cross the Medway to Rochester.

As you approach by train from Strood there are two road bridges.

The one nearest the castle is the 1860s road bridge which the Rochester Bridge Trust built to replace the medieval original.

The other - carrying traffic alongside the railway - was built in the last century, using the supports for the old LCDR line. It ceased to carry trains in 1927, but it was relaid for trains and vehicles as emergency cover if either of the adjacent bridges was damaged during the war.

The Japanese trains have been unofficially nicknamed Javelins, but this is exclusively registered to the Olympic Delivery Authority, so they are officially known as the Class 395 HSTs.

Yet when they enter service they will be the latest in a line of train classes that have fired the imagination of children and men for two centuries.

Schools and Merchant Navy, King Arthurs and a host of other named trains enticed them to travel.

Who knows, in a few years the Class 395 HSTs might be named after Britain’s Olympic heroes - just in time to inspire our 2012 London Olympians.

After all Dame Kelly Holmes gave her name to the first of the trains, and the others are planned to recognise the achievements of speedy Britons.