Thanks to HUKD
www.hotukdeals.com/deals/free-gift-worth-88-when-spend-36-knickers-from-m-s-1984612#post22635384
I bought nine pairs of knickers at £6 each, which came to £54 but at three for two came to only £36. However, the £54 price kicked in the free gift if you spend over £50 on lingerie.
I like to wear matching sets of underwear but some of the black knickers will be fine with a plain black bra.
The free gift set looks nice and will be set aside for my stash of Christmas and birthday presents!