Nottingham Evening Post deputy sports editor Mark Crossley was one of the thousands of people to take part in this year's London Marathon, finishing the course in four hours and 28 minutes. Here he gives his first hand account of the pain - and euphoria - of taking part in the great race.

The London Marathon. On TV it looks like a river of happy humanity, spurred on by cheering crowds, steel bands and some great landmarks.

Once Paula has cruised to her new record and the elite men have had their race, there follows a ribbon of amateur athletes raising millions of pounds for charities.

But what you can't see on TV is the pain.

Back among the four to five-hour runners, I was in the most agony I have ever known.

Looking around me, I could see pain written across almost every face.

This was my second marathon. Had the first been as excruciating, I probably would never have attempted a second.

Last time I ran the London, I was 29 and quite fit. Even so, it took me four hours.

Today is my 37th birthday; my training - about five months' worth - had been dogged by injuries; my teething daughter had kept me awake and I had pulled a muscle gardening a week before the race.

Gardening! At 29, gardening was something old duffers did. Now, here I was, an old duffer standing at the start of my second marathon with a nasty digging injury.

Nevertheless, the first seven or so miles, to Cutty Sark, were enjoyable. Bands played, chirpy Cockneys shouted encouragement, a church bell even chimed the Lambeth Walk.

But with your feet hitting the ground 2,000 times per mile, and a blazing sun overhead, eventually something has to give.

No matter how much pasta you've consumed in the week before or how many bottles of water you've drunk (I took on about four litres during the race and dispensed with most of it against various walls through Docklands) your legs tighten, energy drains, your head can swim alarmingly and joints begin to ache.

My wife first saw me at 16 miles, at Canary Wharf. We had a brief and for her no doubt rather unpleasant, salty kiss.

Later she told me I looked pretty cheerful. But had she been getting the messages from my legs that I was getting, her assessment might have been very different.

"I should have trained harder," I thought, as first my left knee, then my right hip, then my right knee screamed at me to stop.

The second time I saw her was at about 22 miles.

I looked like "death warmed up". There was no kiss this time, just a grunt.

Then came the cobbles past the Tower of London - well apparently the Tower was there somewhere. I was too busy staring at the uneven surface, wincing every time a bump twisted my screaming right Achilles tendon one way or the other.

Had Sally Gunnell thrust her BBC microphone in front of me, I would have thrust it… well, luckily for her she picked on someone else.

By this time, my target of four-and-a-half hours was looking way off but somewhere I found the reserves to pick up the pace along the Embankment and, despite the pain, even managed a turn of speed on Birdcage Walk.

The reasons people run marathons are many. But we all must be slightly unhinged.

One image will stay with me forever. It was of a group of six men heaving the limp body of another onto their shoulders to carry him the final 800 metres.

Surely, any sane person would have stopped before collapsing.

Most of us were raising money for charity - me for the Anthony Nolan Trust - but, to be honest, that probably wouldn't be enough, on its own, to spur me to run 26 miles.

As I swung past Buckingham Palace and the finish came into sight about 200 metres away, I got that surge of euphoria I'd come for and let out a roar. It was obviously slightly over the top as I was answered by a huge roar from the ten-deep crowd along the Mall.

The greatest pain and the biggest high - all in the space of four hours and 28 minutes.

Having vowed at 17 miles and again at 20 and 23 miles that I would never do another marathon, today I'm starting to think, "maybe next year I could just squeeze inside four hours, 15 minutes…"