This 12-year look at London's Spring Impressionist & Modern Evening sales is available to AMMpro subscribers. Subscribers get the first month free on monthly subscriptions. Feel free to cancel at any time before the month is up. Sign up for AMMpro here. This June there are a few works, valued at approximately $100m, in the Impressionist & Modern London Evening sales that are offered with Estimate Upon Request. That's a common feature of these sales over the last three years, as data from our friends at Pi-eX shows. Ever since the June 2016 Evening sales, there has been a substantial portion of the sales value offered with the flexibility of an unpublished estimate. That allows the sales teams at the auction houses to gauge the market in the days and weeks leading up to the sale and transmit what they learn back to the consignors or guarantors who will have to make a final decision about when, how, and at what level to sell.