Thanks for reminding me to mention this Robin – the Valmaine have mostly perished, by mid February, with five out of thirty five surviving. I also tried some Little Gem and about a third survived, compared to three quarters of my Grenoble Red which are both beautiful and abundant. A little harder to pick for the first month and inclined to double head, but a great winter leaf-lettuce (and seed is sold as a hearting lettuce). Also I have tried Winter Density in the tunnel Pete, and survival rates were over a half, nice flavour too, but leaf quality was poor as slugs just love their stems.
In between the surviving Valmaine I planted peas in February (sown modules January of home saved Tall Sugar Pea) and they are now producing lovely shoots, so I don’t mind losing a few lettuce plants! also some Boltardy beetroot sown early Feb. in modules, then planted in odd gaps, are now producing leaves with gorgeous red stalks for salad. As are some plants of Red Cardinal spinach.