"If a big one bites, it will probably be at dusk."

Funnily enough, I nearly didn't go.

When the man behind the counter in the tackle shop explained that while they didn't have any maggots I could have the last of the dying pinkies for free, I had to think fast. Once I've decided to fish with a particular bait, my tactics take shape in my mind's eye and I don't like to be knocked off course. This is a fancy way of saying that too many options distract me - and that I actually prefer to go fishing with one bait rather than two or three.

"Have you got any casters?"

"I'll have a look."

He came back with a small packet and the die was cast. I was happy too. Driving home I started to remember how well casters had fished the season before, responsible for my biggest perch for years. I don't know why I hadn't thought of them before. After that, it was back to work, then some toast for lunch and then a quick lie down to gather my thoughts...and what's this? Gone 2.00pm. What happened there?

I checked the weather, saw that it was going to be terrible tomorrow and then horrible the day after (as I write this the next day, it looks cold but clear - so much for that app) and decided on the spur of the moment to go, even though it was late. I emptied the creel of all the things I didn't really need - second rod rest, scales, weighing sling - brewed a pot of tea and then couldn't find the top of the flask, so settled for water instead, grabbed my 15' rod and new, extra length landing net handle and went out the door.

Then I went back for the casters.

Bloody hell. So that's why it's called a flood plain. The field was sodden with large expanses of thick, claggy mud. At the last minute, I'd decided to go upstream from the bridge where I'd been last summer. Of course, it's a different river. Wider to look at, fewer obvious features, flat and grey. Still, wading across the field I kept checking the river on my left - a couple of interesting looking overhanging trees, almost in the water where debris had gathered; the wintery stubs of a large reed bed that bowed out from the bank; a crease where faster water nudged past a slack.

I got to the top of the stretch and had a chat with another angler, a newcomer to the club, who'd spun the length of the field without a touch. I never like asking to see someone else's membership, but as we chatted he seemed familiar with the club and a water or two. He wandered back towards the bridge and I set up with the pin, 4lb line, a small overcocked stick float and size sixteen hook. I threw a handful of casters in, plumbed the depth and then got to work.

I don't know how I float fished this place before I started using the centrepin. It's not that it's a better reel, it's just that I seem to use it more effectively, even in a current this slow. The float moves more naturally, I'm able to keep better contact with it, I don't spend so much time mending the line (15' of carbon fibre helps here, of course) and I like the way you spin the spool and the end of the trot to bring it back. No bites though, and after 30 minutes I move on.

The sun is almost gone and setting the hedges in the distance on fire when it begins to rain - so lightly that at first I think the widening circles are fish rising. I've seen the owl out hunting on the other bank, stood watching it for a full five minutes as it alternated between long, smooth glides and short flappy jerks as if the bird god was pulling it from above on a piece of string. Occasionally it falls on something, then lifts from the field again while I stand, feeling like Cletus from the Simpsons.

In the final swim I make a final cast. I've taken one of the shot off so the float sits higher in the water which means I can still see it. Then suddenly I can't see it. I strike and feel a powerful resistance, so strong that at first I have no idea what it could be. Conscious of the 4lb line and tiny hook, I'm as firm with the fish as I dare, but still can't get its head off the bottom. I fear it's a pike and then I get a glimpse of a large spade-like tail. For a mad moment I wonder if it's some out of season sea trout, driven barmy from being stuck in the river all this time, and then the head breaks the surface and I see the enormous mouth and breastplate flank. It's a chub. Actually, it's a huge chub. Bloody hell. It's the biggest chub I've caught from this river in 10 years.

I've got no scales of course - and no camera - so I snap a couple of photos with the phone and guestimate the weight. It's certainly 4lbs and might be 5lbs. Given how poorly the river's been fishing for me these last few years, it's an enormous chub. As I lower it back into the freezing river and watch it slip away I am - at least for a moment - completely and utterly happy.