Yes, it defaults to GMT for missing timezones (at least that's what the docs say — the DST offset is apparently being applied separately).

BTW, you can probably generate the timezone files yourself. The sources are normally distributed in /usr/share/lib/zoneinfo/src. For some reason, the european zones are usually not compiled/installed automatically. So, just issue "zic /usr/share/lib/zoneinfo/src/europe" to compile them. Unless told otherwise (-d), this command will install directly into the default /usr/share/lib/zoneinfo, so you'll of course need root privileges.