Last weekend they led the parade down the High Street on Remembrance Sunday, with members playing the Last Post at the Memorial Gardens.
The band returned to competition this year after almost five years and were named as runners-up at the National Championships.
That success saw them invited to take part in the three-mile parade in the City of London on November 9 alongside the winners Romford Drum and Trumpet Corps.
The Traditional Youth Marching Bands Association’s championships were held at Whale Island in Portsmouth, the base for The Royal Marines and their band.
In their first appearance at the showpiece competition since 2015, the talented youngsters won a silver medal for overall performance.
They also secured gold for visual effect – marching and display – and another silver for musical effect.
The achievement was the culmination of half a decade of dedication and hard work since they were transformed into a chromatic band in January 2015.
Chromatic means the musicians play regular orchestral instruments such as cornet, trombone, euphonium, tuba, flute, clarinet and saxophone with drums.
Before then the 17th were a traditional army-style bugle and fife band. Bandmaster Martin Rapley said: “We have practically gone from scratch to second place in the competition.”
There are more than 60 in the band but 34 of the more experienced members were chosen for the contest in Portsmouth, where they stayed on board HMS Bristol, a decommissioned warship.
They played Aces High, Highland Cathedral, The Pink Panther, Swing March, the James Bond Theme and Dambusters March as well as a Royal Marines-style drum show
Mr Rapley said: “Although the other bands knew that we had changed our instrumentation, none of them had seen us perform since 2014 so it was a surprise for them how far we had come.
“We knew that there was no pressure on us, just excitement to show what we have been doing and find out how far we had come.”
He added: “To be able to leapfrog nine other bands and come second is amazing as we are still getting stronger.
“There was genuine surprise from the other bands, and of course everyone wanted to congratulate us for what we have achieved.”
They were judged on five elements: the wind section, percussion, general music effect, accuracy of drill and visual display. The judges were looking for degree of difficulty and entertainment value as well as precision.
The 17th struck up a rapport with winners Romford – they staged a joint performance of the Essex unit’s display piece, Zorba – before the invitation came in to accompany them at to the 804-year-old Lord Mayor’s Show.