walkings all well and good if youve gone from doing absolutly nothing, but you need to be doing more and more if you want to continue to lose weight. you need to be sweating, panting and need to be feeling fucked by the time you finish. this may start off slow if your fitness is very low, but believe me within a month itll have gone through the roof.
start calorie counting. aim for 1500-1800 a day, with a little fat as possible. dont just eat 1500cals worth of pie and chips. ideally, do a big workout (500calories or so) before breakfast, then come home, have porridge, scrambled egg on toast, big bowl of shreddies or 6 weetabix, something along those lines. for dinner something high in carbs again, pasta, rice, baked potato, 2 sandwiches on brown. then dinner something low in carbs, salad, veg and meat. try and take on as puch protein as possible without going daft, so have tuna on your baked pototato or with your salad etc. and if you get hungry between meals dont just starve yourself, eat somethung but try and hold out til your proper meal to fill yourself up properly. fruit, tin of tuna, couple of boiled eggs, are all fairly good snacks.
this is what i did and i went from around 19 stone to just under 16 at one point. (tbh i looked skinny as fuck being so tall) its not easy though, you have to be strict with yourself mate. make a mental list of everything you can eat and everything you cant eat, and everytime you are out or go shopping or whatever and are tempted by something, just think if you have it, thats an extra XXX calories you wouldve lost, and you wont really appreciate it an hour after youve eaten it anyway.
its not easy, you need to be dedicated, if you get pissed off because after eating the odd salad and walking to the shop for a mars bar instead of driving the weight isnt falling off you, you wont get anywhere.