Prowse went on to form Amsterdam in 1999 with former Blow Monkeys drummer Tony Kiley and cousin Johnny Barlow. It wasn't until September 2004 that the band managed to secure a record deal in the form of London based Beat Crazy. They released one album The Journey in February 2005 and three singles, "The Journey" (which hit number 32 in the UK top 40) and "Does This Train Stop on Merseyside" also hit the lower reaches of the charts. The partnership was dissolved by mutual consent in 2006. The band then signed to The Stranglers management company and released their next album Arm in Arm on CIA Recordings in 2008.
"Does This Train Stop on Merseyside" regularly elicited an emotional response from Radio 1 DJ John Peel. Peel's widow Sheila Ravenscroft went on the station after the DJ's death and confirmed that 'He was not capable of playing it without crying'. The song itself got a further lease of life in 2009 as one of the centre pieces of Irish legend Christy Moore's album Listen, which spent 5 weeks at the top spot in his home country.
During this time, the band struck up a friendship with Elvis Costello who used them as his backing band on the Jonathan Ross television show as well as support act on several occasions. Prowse also performed a duet with Costello for EMI Records with a cover of The Searchers' 1964 hit "Don't Throw Your Love Away" for the Liverpool Number Ones Project in 2008. He also picked up a musical icon award on Costello's behalf at Liverpool's Titanic Hotel in November 2014.