It Says Morris On The Door

The Morris Minor was launched in 1948.  It was originally conceived as a low cost Family Vehicle by BMC before World War II, but it's design and development was put on hold.  When the War finished, the plans were pulled from the shelf, re-configured and production began on the new model.  It's price point saw it called "the Vehicle to get Britain back on the roads", and it did that and more.  In it's 23 year life, it became the first UK production car to sell 1,000,000 units, and sold in excess of 1,600,000 when UK production ceased in 1971.
It's birth was not the easiest - as with most British inventions.  The original design for the car was much thinner.  This gave the car a slightly harsh look, and the designer - Alec Issignois - decided to experiment a bit.  He moved the wheels, cut the prototype in two and made the car 4 inches wider to give that now slightly gormless smily look.
However, the tooling had already been manufactured, so a 4 inch plate was inserted giving a rib down the bonnet line.  In retrospect, this bodge actually enhanced the overall design.

Chris Foreman worked for Camden Town Council Parks Department with Lee Thompson.  They joined up with Lee's mate Mike Barson to form The North London Invaders in 1976.
By 1978, after just about everyone in the band had been sacked and re-instated, the line-up finalised and the band re-named themselves Morris And The Minors - a name inspired by the Camden Council van and their band transport.  The name lasted for one gig, before a new name chosen from the set-list and Madness was born.

Their transport was celebrated 4 years later with the release of "Driving In My Car"

"I've been driving in my car, It's not quite a Jaguar"
True when it was launched the Morris Minor cost just under £250.  An E-Type Jaguar of the same age was a shade under £2.500.  So by that comparison, a Morris Minor was tenth of a Jaguar.  But in a mirror of Price vs Sales, the E-Type production and sales were a tenth less than the Minor's

"I bought it in Primrose Hill, from a bloke from Brazil"
Primrose Hill is in the Borough of Camden, so they may well have bought it there.  But as the van was borrowed from the Parks Department, it may just have been liberated from the depot in Primrose Hill.
The Brazil line is interesting, as Brazil was one of the last countries to continue manufacturing Minor's after production ceased in the UK.  I'm guessing Mike Barson knew this, and was just adding in a bit of hidden history in the lyrics.

"It was made in fifty-nine, In a factory by the Tyne"
No it wasn't - all Minors in the UK were built at the BMC Cowley plant in Oxford

"It says Morris on the door, The GPO owned it before"
The name Morris was not on the door, it was on the front wings.  But that just mucks up the rhyme in the next line.
The GPO did indeed own a fleet of Morris Minor panel vans similar to the Madness vehicle

"I drive in it for my job, the governor calls me a slob.
But I don't really care, give me some gas and the open air.
It's a bit old but it's mine, I mend it in my spare time.
Just last week I changed the oil, the rocker valves and the coil"
This is possibly the only song I can think of that mentions Rocker Valves - Bruce Springsteen (in "Racing In The Street") tells us he has "69 Chevy with a 396, Fuelie heads and a Hurst on the floor" but never once mentioned the cam shaft balance settings or his ignition system.

"Last week it went 'round the clock, I also heard a little knock.
I dented somebody's fender, He learned not to park on a bender
I've been driving in my car, it don't look much but I've been far.
I drive up to Muswell Hill, I've even been to Selsey Bill
I drove along the A45"
and in the video for the song he didn't stop to give the Fun Boy Three a lift back to Coventry - again  it's the little details.  The A45 does indeed go to Coventry, so Terry, Lynval and Neville were hitching on the correct road (even if their one-time label mates ignored them)

"I had her up to fifty-eight"
This is good going for a nigh-on 20 year old British car whose top speed (in later Series II guise) was 61 mph

"This copper stopped me the other day, "You're mistaken, " what could I say?
The tyres were a little worn, they were OK, I could have sworn.
I like driving in my car, I'm satisfied I've got this far.
I like driving in my car, it don't look much but I've been far.
I like driving in my car, even with a flat tyre.
I like driving in my car, it's not quite a Jaguar.
I like driving in my car, I'm satisfied I've got this far"

"I'm satisfied I've got this far"
At the risk of over-thinking this line, could this be a philosophical review of the last 4 years - 12 singles (10 in the Top 10) including a Number 1, 3 Top 10 albums, and one of those unimpeachable compilation albums in the shape of 'Complete Madness'.
Yep, I'd be quite satisfied too.

Then again, maybe it's just a decent line that rhymes with "Driving in my car"