Nigel Burch plays a banjolele-led blend of punk, folk and cabaret jazz. He regularly tours abroad, and has been a licensed London Underground busker since 2003. Following a tour of Germany earlier this year, he applied to renew his licence, but was astonished to be refused an audition. The banjolele, he was told, is an "undesirable instrument".

Emails forwarded to the London Underground Buskers email list confirm that a list of "undesirable instruments" exists. It includes the banjo, though not specifically banjolele, which Burch pointed out to no avail – following clarification of what a banjolele actually is, it now appears to be on the list, although the ukulele is not. The Musicians' Union was called in and received a denial from TfL that there was any such "undesirable instruments" list, contradicting earlier TfL emails to Burch, and effectively ending any sensible discussion of the matter.

This is entirely in keeping with TfL's management of the busking scheme since it went in-house two years ago. Since then, direct and indirect busking income has been slashed by arbitrary bans on CD sales and distributing business cards. There is no more online pitch booking. Instead, buskers must call a premium rate telephone number during office hours to book slots; an ad hoc cancellation/pitch swapping mechanism via the email list was only grudgingly accepted. Annual licence renewal is now highly bureaucratic – the cut-off date for reapplication falls (counterintuitively) some time before the actual expiry, as more than one now ex-licensed busker has found. Fail to play a minimum number of pitches in a given period and the licence will be revoked, but buskers have not been told what that minimum number for that period is, with serious implications for those offered touring opportunities.

Like Burch, most buskers are professional musicians who busk between other gigs. Rumours abound among the community that Burch isn't the only experienced musician mysteriously unable to pass the latest round of auditions. A (superb) flamenco guitarist named Jacob Carey who, like Burch, was also trying to renew his license following a recent international tour, did get an audition but – astonishingly, to anyone familiar with him – failed it. Meanwhile for those still on the scheme, busking seems less attractive. A paranoid person might think that TfL were trying to get rid of us.

One thing that may shed some light on all this is another list which definitely does exist and has been distributed to all buskers. This one concerns specific instruments banned on specific pitches. It includes items lsuch as "robotic sax" – which appears to be there specifically to ban a guy called Steve Aruni, who plays guitar along with a latop-controlled modified sax-playing Henry the Hoover. Genuine health and safety concerns may lie behind some of these specific pitch bans; others seem totally arbitrary.

What's going on? Here's my guess. From its inception in 2003 to July 2008 the busking scheme was outsourced to Automatic Management, an independent artist management company that also handled Gene and other bands. Being artist managers first and foremost, Automatic tried to protect the musicians on the scheme from random nonsense such as the Notting Hill Gate station manager's dislike of all buskers and arbitrary ban of the flute from that pitch.

Since the scheme has been taken in-house, it is being run by middle to low-level TfL bureaucrats who have no idea how to deal with either musicians or the fact that some station managers opposed the scheme from the outset (for example, at Notting Hill Gate the pitch is now permanently closed).

Hence the partial litany of troubles that seem designed to cull our numbers, especially those depending on the income, and to discourage all but the most laidback of hobbyist buskers.

It looks like the TfL strategy for handling the busking scheme is to turf out (and keep out) as many of the old guard as possible and give the licences to new people who, they believe, won't cause trouble by trying to turn the scheme back into something you can actually scrape a living from between gigs; new people on the scheme won't even know that such a thing was once possible. As such, the "undesirable instruments" list may well just mean "anything unusual played by an experienced busker trying to renew their licence".

Yet the scheme itself was originally set up as part of a recognition that busking is inevitable. It has widespread support among the commuting public and its removal would mean a massive waste of resources for both station staff and British Transport Police. TfL repeatedly assure us that it is committed to the future of busking.

As things stand, however, many licensed buskers feel that we all play undesirable instruments.

Wayne Myers is (still) a licensed London Underground busker