Thank you everyone for your replies. If nothing else, I don't feel so alone now.
I've done a lot of thinking this week. I guess the upshot is, this is happening and I need to accept it. I am going to have to eat less. I don't want to - but I think I have to. I have also cycled and power walked and both caused little, if any, knee pain (knee diagnosed after MRI by Consultant, Limpy).
Hugs - I can really identify with crying over it! The lack of control over my weight and frustration I feel because of that actually keeps me awake with worry at night

Let me know how you get on x
Tiger74- Thanks for that, I know very little about thyroid problems but reading up, it could be a possibility. I told my GP recently what was happening (before I jnew about thyroid problems) but she weighed me, told me my BMI was ok and seemed unconcerned - may have to revisit.
JuJu - I eat a lot more than you by the sounds of it and annieb I suspect, on reflection, I eat more than I think - typical day is a ceral bar. Two slices of toast with two eggs - mid morning to last until the evening. Night time is a beer or two, bag of crisp and my tea - jacket potato or salad or own prepared meal. Takeaway once every two to three week. Occasional biscuit, luckily not desperate for biscuits and chocolate. Oh I make my own smoothies. No idea if I eat more or less than friends..
Hurdity - thanks, reading your reply again reminds me I have to cut down.
Thank you everyone, again for support and inspiration. xxx