I've designed hundreds of bearers and padstones and I can say with 100% certainty that you do not need a 1m long bearer.Well, just talked it through with him, and he's convinced.
Said he raised an eyebrow too when the software gave him those dims, but he checked by hand and it was right. Stated that there was roof loading, floor loading and a potential mezzanine on the attic deck... all adds up.
So, I'm going to ask the builder if he still want to use bearing plates instead of precast lintels knowing that the plates will weigh 40 odd kilos... Though I expect the relevant lintel would weigh even more...
Thanks for all your replies.
John.
But hey, if your SE says you do...