how do you tell a plum from a pear when not in leaf?

Yesterday this search on google brought up no results, at least in the first 3 or 4 pages worth.
I needed to know because I came across some of the cheapest fruit trees I've ever seen on Saturday at £5.50 each. I've been wanting to put some kind of fruit tree in the garden for ages, toying with the idea of a very mini forest garden. Anyway, in what for me is a mad spending spree I bought a cherry, 3 plums and a 2 pears. I carefully stacked them out the back to await planting.
It blew up a hoolay that very night, "the wind blew as t'wad blown it's last" etc and all the labels blew off. The cherry was easy to sort out --paler bark and a much more delicate look all together. The other 5 bare root year old fruit trees were pretty much of a muchness. After careful studying I'm hopeful I've sorted them out. There was a very slight pale fleck mark running vertically on the bark of 2 of them and the other 3 seemed to be completely self coloured. So I've planted the 2 flecked ones (pears I hope) up at t'allotment, while the 3 plums are going to be trained against the fences in the garden. The cherry is going into a very big pot while I think about it.

I've been up the allotment in the dimsky 3 nights in a row now. The last two nights I've been there from just after 5 till 7o'clock. Even though it's been breezy up there both nights, I've been busy enough to stay warm. The view is phenomenal. The topsoil is 12-18 inches of really nice loam over a red clay subsoil. Things begin to recover a bit from the brutal strimmer haircut it had before hand over and I think I've got raspberry canes too. And one very neat row of oniony things. My body aches all over, but it's a muscular, I'm getting fitter type ache, rather than a my joints are going to catch fire or my tendons are getting shredded type ache (so far anyway).

oh also saw a very bright shooting star tonight. that or some space hardware dropping back to earth. It wasn't even properly dark yet and the moon was full. I must check if any showers are due.