I have found a seed packet of tomatoes which were 12 years old so I put some seeds on a wet paper towel and left them for two weeks in a warm place and all have germinated.
tomatoes are amazing, I've had them pop up the garden after being through the compost heap. They can also survive passing through a human,and sewage treatment and germinate.
Hostafan my neighbour works at a sewage works and they have strawberry and tomato plants cropping up everywhere... He says they are best fruits you have ever eaten!!!
Also Chilli seeds can be kept for years and still germinate. I'm using 5-year old seed this year. Mags
"The oldest carbon-14-dated seed that has grown into a viable plant was Silene stenophylla (narrow-leafed campion), an Arctic flower native to Siberia. Radiocarbon dating has confirmed an age of 31,800 ±300 years for the seeds"
So there's hope for those seeds at the back of your tin yet!!
I'm using tom seeds I saved in 2003. Kept dry and at a consistent moderate temp, they will remain viable. If older seeds prove a bit stubborn, soak them overnight in warm water.
Nature is a wonderful girl, isn't she?