<Yesterday, actually.>
Tried to start the kit car to drive home form work and it started to turn over then there was a fizzing noise and a smell of sulphur and all the leccy disappeared.

Took a bulb out of the fog light and used it and a random bit of wire to diagnose the issue. Quickly realised that the battery had suffered a sudden and terminal failure.
Phoned Mrs. KW, who said she'd pop over in the Jag with some jump leads rather than wait for Green Flag.
Mrs. KW gets forced off the road by a disciple of Onan in a French shitbox, bursting a tyre. XE doesn't have a spare tyre.*

So, double "wait for recovery truck" comedy ensues. Guy turns up to me in a van only, jump starts it (took 2 packs in parallel), pronounces battery dead so drive home without stalling it is.
Road closed, so end up taking the XC route and getting lost. Green flag app which I'd unsuccessfully tried to install to summon recovery appears to have borked my phone so no sat nav. So, multiple turns down multiple blind alleys and farm tracks all negotiated without stalling.

Meanwhile, AA turn up to assist Emma only to find they don't have a temporary wheel to fit the XE, so now awaiting mobile tyre fitting guy.
Finally both got home at 9 PM.

Out of hours tyre fitting charge is approximately the same as the cost of a spare wheel**. False economy, Tata.

*- technically, it has a spare alloy in the garage which I've not yet got round to fitting a tyre and pressure monitor to.

** - Bot not from a Jag dealer, naturally.