The "No. 10 source" is likely Dominic Cummings... Many commentators stating none of the "leak" reads like something Merkel would actually say.
Indeed, and clearly it's somebody who knows very little about Mrs Merckel, because the language, the tone, as well as the content is something which simply does NOT match her way of doing at all as everybody with a bit of understanding of German politics immediately noticed.
But it's clear why these lines were put in exactly her mouth in the Cummings scenario: they need to put blame for the brakedown on someone in the EU and it's far easier to blame to Germans than it is to blame say the Dutch of the Danish… the Irish would be the most logical 'source' for this fabricated message of course, but sadly that would cause too much problems in NI, so Cummings probably decided not to go for Varadkar, whereas the French would have been an option too, but President Macron is very likely to put the tape out of the discussion and expose the lie, so the choice fell on Mrs Merckel as the Germans never disclose telephone conversations.
Nevertheless, this shows again you what a pathetic advisor and pathological liar this guy is...
Another one is the threat to several of the smaller EU nations (notably in the Baltic) that they will be moved to the back of the line for future collaboration if they approve the extension, and to the front of the line if they veto it? ROTFL...Talking about overestimating yourself!
Besides, since the EU27 is rock solid, that means moving the entire EU to the back of the line then or what? Bodes well for that FTA that BoJo dreams of …
Oh wait, that's the next thing to fall through: after the 'we can have whatever kind of relationship we want after we vote for Brexit because they need us more than we need them', and 'this deal is going to be the easiest deal ever', to 'we don't want a deal, but a FTA'... soon it's also going to be 'we can't conclude a FTA with the EU'...
Let's just throw ourselves into the arms of Trump's USA right away, shall we, because THAT's the obvious end goal, isn't it?
Bye Bye NHS and hello clorinated chicken!