When I was on breakdown duty at the garage I worked at. Breakdowns just after filling the tank were always down to putting the wrong fuel in.
A diesel engine really won't run if petrol has been put in the tank.
A petrol engine with diesel in it will run, just. But it will make its own invisible smoke screen!!
It's so easy to misfill the tank with a diesel engine vehicle, it's untrue. My wife managed it a couple of years back. It's not good putting 50Ltrs of petrol in a diesel Vauxhall Astra GTC. Luckily she managed to get it home, just. I then had to pump out the entire tank contents then refill with diesel. It ran like a bag of spanners for a couple of tanks of fuel. It also had a pile of codes logged too. However it never went bang afterwards, but it's now made way for the Kuga, so I don't know if there were any lasting effects on the HP pump.
Yup, spot on !.. another side effect of the incredibly often petrol in diesel is severe damage to the catalytic converter that can take from days to a month or so to manifest. Almost always the 'cat' is captain cooked. My wife is also guilty of petrol in her Citroen AX Diesel.

.... how long the problem takes to manifest after the actual filling is proportional to the amount of diesel in the tank prior to filling. (she parked over a grate near the kerb when it finally 'died' I was extremely environmentally friendly cough cough - and the drain allowed a convenient place to get rid of a tankful of petrol..... don't tell the tree huggers ! - needs must etc etc....
For the OP,
The specific gravity of the various fluids are in order (heaviest to lightest) water - diesel - petrol
IN a perfect still situation with water, diesel and petrol in a tank - water would be at the bottom, then the diesel, then the petrol, however, what happens in reality is a churned mixture of diesel / petrol with water being more often in the form of 'bubbles' or globules. Most fuel is returned to the tank in a constant circulation leading to gasoil / gasoline mix./
The big danger as well is that the diesel HPFP(VP37) on the L series is lubricated BY diesel (as are all diesel pumps!), as are the injectors,
also the cylinder bores rely on diesel for 90% of their lubrication. The far far higher pressures of a compression ignition engine (diesel) when petrol is mixed with diesel can cause explosive HGF also - as well as damage to the other lubricated components.
Yes, there is a minute possibility that 'something else' occurred -
However - in most things automotive - Occams Razor is a good guide to follow

it has served me well over the years.
Joe