The Observer ran a report last weekend about 'the hidden gems to discover off the beaten track.' While the commentary reveals the London-centric attitude of the national media (Blimey! Check out that Velazquez at the dingy parochial country pile! Who'd have thunk it?), it does help to emphasise the rich diversity of museum and gallery collections up and down the country. You can read about The Observer's selection here, but there must be many more. My vote would go to the Constables and Gainsboroughs at Christchurch Mansion in Ipswich, and the Attenborough collection of Picasso ceramics at New Walk Museum, Leicester. Where are your hidden masterpieces?