You do indeed lose baggage waivers. I regularly fly SAV-LHR and with silver status got a bag waiver. Following Delta's decision to have the ATL-LHR flights operated by Virgin the privilege is lost. Virgin does not match Delta's privileges. Same would apply if you hold the Delta Amex card, baggage waivers on that do not apply to codeshares.All of this has come about because of a decision by Delta, not by any change in what the customer does.

To add insult to injury Virgin's check-in at LHR is badly run and while the linking of Virgin and Delta's websites has improved it's still bad.

On Delta you can check your bags on-line and pay for them as well. When you go to My Delta to check in you get forwarded to Virgin but get no chance to check your bags. You have to go to the bag drop at LHR and then if you have to pay for an extra bag go somehere else to pay. It took us over an hour to check in because the payment desk was unmanned and we had to go to yet a third queue. The Delta ticket receipt said I could check 1 bag at LHR but for the leg ATL-SAV I could check 2. Presumably they think I have supernatural powers and can cause an additional bag to magically appear partway through my journey.

Oh and another thing while the Virgin site will allow you to print boarding passes it will only print your first sector, if like me ATL is not your final destination hard luck. whereas Delta would produce boarding passes for both sectors at check-in Virgin don't so on arrival in Atlanta you have to find a kiosk and print yourself one. For some reason the My Delta app could not download the boarding pass, so another ding against Delta.

All of this means my four year loyalty to Delta for transatlantic travel is at an end.