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We report on a study of long-term flux variations in a sample of more than1000 AGN observed with ROSAT and in the XMM-Newton slew survey. Over a periodof 3-19 years, NLS1 galaxies as a class are found to be only slightly morevariable than broad line Seyfert galaxies, despite the strong short termvariability seen in some bright nearby NLS1s. Contrary to expectations, it isSeyfert II galaxies that exhibit the greatest flux volatility. One particularSy II, which has brightened by a factor > 300 over 15 years, has been monitoredin detail with Swift and XMM. The spectrum is extremely soft (kT \sim 60eV)consistent with pure thermal emission from an accretion disk and reminiscent ofROSAT observations of the NLS1,WPVS 007. We show that this is likely to be a"true" Sy II, without a BLR, and speculate that in its new high luminositystate we may be able to witness a BLR in formation.

Long-term AGN variability and the case of GSN 069