There are two reasons why your tomato should be so tall with only one truss.
First, the first trusses were 'lost' because it was planted out at the wrong time, basically too early. You should always wait until the first truss is in flower before planting.
Second, is there a possibility of lack of full light, so your plant is becoming etiolated? Growing to 5ft tall so early in the season is odd for any tomato variety.
As far as next year is concerned, the best variety for general use is Gardeners' Delight which is dependable, heavy cropping and one of the best flavours. It is a small tomato but larger than a plum.
As for this year, what commercial tomato growers do is to lower the bottom part of the plant to allow the plant to grow higher/longer to continue cropping. You could try this. Alternatively if you haven't pinched out all the sideshoots, leave one forming lower down to become the new 'leader' and pinch out the main plant at its present height.

this year I put 2 grobags on a table and instead of growing as a strict cordon allowed a sideshoot to develop and stopped it at the first truss -- they seem fine and i'm picking red tomatoes already --- its similar to what Bertie says and works very well

My thanks to you both. The plants only went in growbags outdoors about 3 weeks ago, but I think the "seeking full light" is my problem. Unfortunately I have already pinched out all the sideshoots. It's my first attempt ever so I will learn for next year! Thanks again.
DavidT.

Don't give up on the sideshoots as more will grow lower down, particularly if you pinch out the top.