1 - chomping back picnic-basket pork fancies

"Look! Some of these boats have hanging baskets on them!" said Huw in tones of pant-scorching glee.

2 - pant-scorching glee

* 'to chomp (sth)' = to chew large amounts of food noisily.
* 'to chomp (sth) back' = to chew large amounts of food noisily and swallow them.
* 'pork fancies': not sure, except that it's obviously some type of food/snack.
* 'picnic-basket' (adjective) = of the type and size you'd pack for a picnic.
* 'pant-scorching glee': I suspect (but am not certain) that this is a term the author's invented, where 'to scorch one's pants' means 'to leave a 'burn' mark (brown stain) in one's underpants due to hot-farting'. If so he's probably saying that the man was so excited that he/others around him were farting.

The article's obviously written by someone who isn't a fan of the Royal Family and is ridiculing the flotilla and those who took part in it.

"Вы только посмотрите! На некоторых лодочках даже корзиночки с цветочками!" -захлебываясь умилением, провозгласил Хью.

(если нужно жестче и/или сохранить тему нижнего белья, то вспомните про "радости полные штаны")

Re article - Nope. Didn't even read it!

As for BBC's attitude towards the Sachsen-Coburg und Gotha lot, it's a safe and aww-guaranteed subject that the mythical Great British Public cannot ever tire of. (Also remember the Royal Charter).