Covenant income per the Covenants Book

How many of us have calculated Covenant income using Covenants? Here's what I've done:

We have a spring-summer covenant with 1 established mage and 6 recently gauntleted. We use Triamore as the basis for the covenant. As it stands, I would guess this is a typical covenant for income, in this case the source is Agriculture with a few add-ons. The extent of the agriculture is probably a little less than the example in the book ("a large tract of wheatfields in Westphalia, with a half-dozen villages") but the few add-ons, I reckon, bring it up to typical. The book defines typical as an income of £100. Calculating a covenant according to the rules with this number of mages and with a few labourers and craftsmen, comes out at around £200. I can tweak things by adding a few more craftsmen but the model is not very sensitive to this and its very hard to get costs down near to £100.

Is your experience similar? If not then perhaps I've made an error. If so, then is the model broken?

GIven the disparity, I've tried to find some reasonable medieval data on agriculture: rents, yields and holdings and prices. Using these I can get an income of £140 in a typical year, which is closer to my target of £200. I can add on to this about £10 for other rents, such as pannage, and the manorial court. I am still £50 off but this is part of the long-running story that money is tight. One of the magi is enhancing the crop and fortunately the figures I have include yields in very good years.

Interestingly, of the £140, £100 comes from selling the output of the Lord of the Manor's demesne (which is 10% of the manor) rather than the rents gotten from the tenants of the other 90%. Apparently this may be realistic when grain is short (4s or 5s per quarter (28lb) in around 1220 according to one source - this seems very high if output is around 5 bushels per acre - where the bushel is two quarters). However, I am continuing to gnaw away at this problem as it seems to contradict the trend I've read of where work-rent and produce-rent became replaced with money-rent. Why would you commute work in the fields for cash if that work produces excellent profits following the sale of the produce (assuming good weather and steady markets). I suppose the answer to that might be that the money-rent is constant (though not totally reliable if the tenant is bankrupted as a result) whereas produce can fluctuate considerably in value.

Any thoughts?

This is maybe sort of peripheral to your main query, but you can easly raise that baseline of £100 to £115 by RAW, and perhaps more by fiat:

Well Gerg I'd never noted that. It is a bit of a fudge, as you note. Thanks for the input.

Our Magi should have living expenses at the same sort of level as a low to middling noble I would surmise. As such, they would expect to be each be supported by a number of manors: though they may have fewer men at arms (there are 16 grogs in our turb) there are still significant costs. Expecting 7 of them to live off one manor is not realistic. That means I have to fudge things in one way or another (which incidentally sugests that the Triamore setting could never have worked). I'll keep on at the problem till I'm happy.