If you are new to EHESS, please read this article about how to make a standard EHESS order first.
If after placing an EHESS order you do not get a successful order automatically, you will be given a popup (see below). If you want to order manually through the DCS you can click 'Resubmit to BL' which will send a manual email to the BL.
What this new functionality means for you, is that when the EHESS API fails to find a direct match for an item you’re looking to order a copy of, you can still submit this order to the BL and they will be able to complete a more thorough search, as well as being able to provide Copyright Fee Paid (CFP) copies from St Pancras holdings that they own. For outsourced scanned (non-CFP), the BL can supply from their entire collection including legal deposit and items in the reading room that might not otherwise be available.
There are a few important things you should know about this functionality. Firstly, as the BL will be carrying out searches in person for this content, they may take longer to fulfil than the SLA they currently have for standard orders, so please be aware of this when ordering. Secondly, as these orders bypass the standard matching process that the API currently carries out, the bibliographic details of the order will not appear on their British Library On Demand account, they will only be visible via the DCS. Finally, as the orders will be manually fulfilled, it may be the case that you do not receive notification of the Copyright Fee (please contact email@example.com if you wish to check the Copyright Fee - quoting your BL order number from the DCS). You can check the fee by looking up the book or journal (not article but the whole journal) at http://explore.bl.uk/ and selecting the 'Details' tab and looking under 'Rights'.
For those of you who used ARTEmail this is the same as functionality that was provided through that service, so may well be familiar.