Mine are doing great.

Can't say I've noticed this in my part of the world. All roses which normally smell good are doing so. I was at Mottesfont Abbey (national collection of old roses) in early June and there was no lack of scent there.

Did you have a dose of 'flu or suchlike near the start of the rose flowering season? That (if you're unlucky) can damage the human olfactory senses for a surprisingly long time, well over a month.

Resin

Interesting idea, pineresin, but actually:
(1) the roses are smelling less fragrant than usual relative to other flowers;
(2) I am not the only person to have remarked upon this.
It is possible that this phenomenon is restricted to London area but that still begs the question, Why?

I don't know how illness might affect the ability to smell different flower scents, but "not the only person to have remarked upon this" doesn't necessarily rule out illness. At least up here (Northumbs), there was a rather nasty bug 'doing the rounds' in early to mid May, which an awful lot of people came down with. That was actually partly what prompted my suggestion.

Resin

Maybe the roses have finally given up trying to compete with all that traffic pollution? I'm told that's why my robin sings in the middle of the night!

"trying to compete with all that traffic pollution?"

Isn't there supposed to be less since KL's congestion charge came in?

"I'm told that's why my robin sings in the middle of the night!"

That's the streetlights doing that - keeps them awake at night!

Resin

Shrubs'n'Bulbs - apparently pollution is much less than it used to be. Before the 1950s and the Clean Air Act it was impossible to grow evergreens in London because of the pollution. Roses were actually quite good at handling the pollution (the sulphur helped keep them free of blackspot); that's one reason why they were so popular.

Anosmia is a sign of vitamin deficiency (the one you get from carrots I believe.) It could also be a sign of some dysfunction in the brain, maybe the onset of a disability. I forget which.

I hope that rather than unduly upset you you fell fore warned. Good lick if not sniff.

Roses release their scent most strongly when the flowers are warmed by the sun. In cooler weather, or in rain, the scent is far less noticeable, in my experience.

We still don't have an answer. Ornata - as I mentioned in my original post, the amount of rose scent was very disappointing when we did have some warm, still days two or three weeks ago. But maybe the cold weather in May triggered something (or failed to trigger something) in their biochemical make-up so that they have ended up producing less scent on warm days?

I haven't noticed very much scent from my roses either this year. As mine is a climbing rose on a wall, I've noticed its scent wafting in the past on hot sunny days. We had the occasional pleasant day but none recently which I would describe as hot. It's the same with the sweet peas - I have only noticed their scent from a distance on a sunny day. And with all this rain we're getting, lately not at all.