The weird thing is that she MUST know she’s talking cobblers. She lived until fairly recently in Netherwitton Hall, in the heart of Northumberland sheep country. Not sure whereabouts she lives now, if she ever gets out of London, but unless she keeps her eyes tight closed she must know that there are plenty of larger lambs around now (probably produced in a more sustainable way than Easter lambs too, as they can be sold off grass).
Shows how much respect and understanding she has for her constituents (ie. me).