"Eton Rifles" -- The Jam:

Sup up your beer and collect your fags  There's a row going on down near Slough. Get out your mat and pray to the West.  I'll get out mine and pray for myself. Thought you were smart when you took them on,  But you
didn't take a peep in their artillery room.  All that rugby puts hairs on
your chest. What chance have you got against a tie and a crest?
Hello-Hurrah - what a nice day for the Eton Rifles.
Hello-Hurrah - I hope rain stops play for the Eton Rifles.

Thought you were clever when you lit the fuse, Tore down the house of commons in your brand new shoes,  Composed a revolutionary symphony,
Then went to bed with a charming young thing.
Hello-Hurrah - cheers then, mate. It's the Eton Rifles.
Hello-Hurrah - an extremist scrape with the Eton Rifles.

What a catalyst you turned out to be:  Loaded the guns, then you run off home for your tea  Left me standing like a guilty schoolboy. What a
catalyst you turned out to be Loaded the guns, then you run off home for your tea Left me standing like a naughty schoolboy  We came out of it naturally the worst  Beaten and bloody, and I was sick down my shirt. 
We were no match for their untamed wit, Though some of the lads said they'd be back next week. Hello-Hurrah  it's the price to pay to the Eton Rifles. Hello-Hurrah - I'd prefer the plague to the Eton Rifles.

"The Eton Rifles" as such, do not exist: the cadet corps of Eton College is the Eton College Officer Training Corps, Eton being a famous English public school that is regarded as the epitome of Britain's privileged 'elite'. The song itself recounts the difficulties faced by the unemployed and lower paid working class in protesting against a system loaded against them.

The song recounts a street battle Paul Weller had read about in the newspapers concerning elements of a Right To Work march going through Slough in 1978 breaking off to attack pupils from Eton College who had been jeering the lunchtime marchers , rashly thinking that a bunch of 'posh schoolboys' would be an easy target: only for the outnumbered but far fitter college pupils to give them a beating. 

Literally, the first part of the line means "drink up your beer and collect your cigarettes", though in this case it is likely a double entendre referring both to a group of friends hurriedly leaving a pub, and to the British boarding school practice of fagging; a hierarchical authority structure in which younger students acted as personal servants to those in higher forms.    

            

The documentary of Eton College . Interviews with beaks[teachers] and house masters and boys.