Fuck it! Do I just have to accept that I am too old and slow?

Brilliant, well done! Looks like there's plenty of life left in those legs.

Ahem! Attention please !*

I have just looked at my training record and found that my average pace has increased from 5.35 mph in Jan to 5.95 mph in June.

OK, not breaking and landspeed records but I am going in the right direction

IrianofWay I'm not sure age has much to do with it. I started running 3 years ago age 48, and am faster than quite a few younger women in the club. I ran my second marathon in March in 3H35 which isn't bad, and faster than the one I did the previous year, so your speed doesn't necessarily decrease with age. However, I have a low resting heart rate and that helps a lot. If you do speed work (intervals etc.) that should help, but maybe you should aim more for longer races as it is endurance that increases with age rather than speed.
Regarding body type, most of the fast sprinters are tall and muscly, but most marathon runners are small and wiry. I'm tall and slim so not necessarily built for endurance but I prefer longer races to short ones.
Have you ever tried running a HM for example?

Walk breaks in training and in competition. Sounds crazy and does take a little getting used to, but really does make you faster. Try downloading his book "marathon, you can do it". Tells you very precisely how it works and how to calculate the walk:run ratio that suits you. Could be worth a try, really changed the game for me.

I'm going to weigh in with a couple of different ideas. Firstly I'd suggest having a look at Jeff Galloway's training plans. He advocates 30 second walk breaks during the run. Sounds crazy but many, many people have found this makes them faster. Especially the more er, mature runners. Might be just what you need to get a faster time.
My other thought was don't go faster, go further instead. I realised that a speedier time wasn't going to happen so I moved to ultra marathons and trail marathons. Instantly gave me a new challenge and now it's one I can achieve. Worth a thought? The ultra community are very welcoming too

Think you will have to tell your legs that you're in charge then Irian! When is your half?

This is another good read: The Art of Running Faster.

I managed to get a lot out of it despite just being a casual runner. One of the best pieces of advice was to run for the way you feel. So if you planned to do a long slow run but feel up for a fast short one, change your plans. If you went out for a quick jog but feel awesome, keep going. Also it said that short effective runs are better at improving speed than trying to run for longer and longer distances.

I went out for a 5 mile easy run this week but ended up doing 3 miles at a much faster pace as I felt I could do it. Unplanned, I just changed it as the run began.

I dont especially care
actually I think I prefer it if you're not interested and then I wont get drawn into wasting my time explaining what is really only basic physics/science to people who cant seem to grasp simple concepts

I think research has shown that losing weight will make a difference to your times, but of course there are many other factors for each individual and as none of us have the luxury of a coaching team dedicated to our needs we'll probably never work them all out! I am tall, 6ft 1 but my 5ft4 friend is faster than me! I think I would be faster if I pushed harder, and I think a coach or personal trainer would help there, or being in a good running club, which I don't have. And I guess great nutrition, plenty of rest, no stress...no likely with 3 kids, a dog and an OU degree! OP I can only say don't give up, tweak what you can and keep training, I hope you can make some progress still and can carry on enjoying your running.

Perhaps if you hadn't been so rude in your post I may have been more interested in what you had to say.

I assumed tall people made better runners as they have longer legs, hence a longer stride? DP walks much more quickly than me, and I walk much more quickly than little DS
we are talking about bio-mechanics here, afaik the influence of leg length on walking speed differs from it's effect on running speed.

I'm not sure what the optimal height/leg length is for running but (afaik) long legs are only an advantage up to a certain point.
The best runner is the one for whom all the variables are optimised

I wasn't suggesting that a heavier person will always be faster than a lighter person, I am saying that body weight is one of the variables which affects running speed.
In order to look at the effects of a variable you need to eliminate the effects of other variables, obviously this is abstract thinking, but it's how basic scientific experiments are conducted...doesn't anyone get this?

I assumed tall people made better runners as they have longer legs, hence a longer stride?

DP walks much more quickly than me, and I walk much more quickly than little DS.

I also walk more quickly in higher heels as it lengthens my stride.

Is this wrong?

why do I even bother

suzanne it is highly unlikely that all other things are equal as we are all individuals. You can't look at people and decide skinny person =fast and fatter person = slower. it isn't that simple and you can't just caveat it with all other things being equal because it isn't that simple.

I can't help but think that assuming two runners start, for example, C25K at the same time and train as much and as hard as each other, generally the 8 stone runner will find it easier to be nippy than the 12 stone runner
some people just have better engines, blood with higher oxygen carrying capacity, more efficient heart and lungs etc etc, some people have a large and fast response to training, some have a small and very slow response.
If all the other factors which affect running ability are held equal then the lighter person will be faster, because less fuel is required to transport a smaller mass over any given distance

I'm not convinced on the theory of a 8 stone runner being faster than a 12 stone runner
fgs it's not that hard is it??
do you understand what is meant by 'all other things being equal'??

So how does the tall lean vs. short lean theory work for Usain Bolt

I refer you to my 'assuming that all other variables are held equal' caveat

obviously there are many variables which affect running economy and the weight of each variable will vary from person to person

and presumably in the case of elite athletes there is something different or 'extra' going on

I'm not convinced on the theory of a 8 stone runner being faster than a 12 stone runner. I did C25K with a large group last year and some people were seriously speedy and others like myself were slower and remained slow. We have some people in my running group who you just need to look at to see they would be classed as overweight and they are really fast.