On 2016-05-15, newshound wrote:

I imagine the extra joists have been added at some time in order to
adjust the level of the bathroom floor. You don't state the age of the
property (other than that with L&P it's presumably well over 50 years
old) but in my 1780's cottage movement in the 2x2 inch oak joists means
some of my floorboard would be all over the place without packing.

I think the rest of the house is 1910s & the kitchen & bathroom were
added at some point (well over 50 years ago). Next time I get a
chance I'll see if I can "periscope" (torch + phone camera) to see
what's happening at the ends of the joists.