clash between bazaar and subversion

I have an entire system locally versioned using Bazaar. I have some small sub-directores, within that system, also version controlled under subversion using tortoise client 1.62. (The subversion repository is a remote, the Bazaar system is local.)

If I attempt to use the bzr 'revert' command to back track my local copies- and my revert includes any files also controlled by subversion I get an error. Here is a simple command and the error I get back:

C:\Program Files\Client>bzr revert somepackage\somefile.txt
bzr: ERROR: This client is too old to work with working copy 'C:\Program Files\Client\somepackage\somefile.txt'. You need to get a newer Subversion client, or to downgrade this working copy. See http://subversion.tigris.org/faq.html#working-copy-format-change
for details.

If I remove the '.svn' files that subversion scatters all over the place then Bazaar works fine, but this disrupts subversion...

Other bzr commands work fine.

Is there any better work round? Obviously I don't understand why the two system clash , I would have expected them to operate orthogonally - is there some obviuous reason why I would have expecte trouble? (My bzr add commands are pretty indiscriminate and probably add everything - does that matter?)

many thanks.