In addition to the OP, can anyone recommend a canvas tent which is the size mentioned but that isn't a bell tent?
there is frame tents like this: here
or a Dutch Storm tent: like this 6 person tent we have the smaller version - the Eldorado which is a 4 person sleeping area - but that great for the 2 of us.
In contrast to the advise above that 'canvas is a liability in the UK' - having got Canvas tents now, we tend to use them when away camping rather than our nylon tents.
In terms of tents we have:
(Canvas) Vango Force 10 (mk4) - dated late 70s
(Canvas) British Airbourne division tent (1944 pattern canvas)
(Canvas) 4 person Frame tent from the mid 70s - bought for £10 off ebay and get used at festivals like Bloodstock & long weekend motorsport events were we are away 2 nights
(Canvas) Hypercamp Eldorado - used in bad weather as the pyramid design is really stable in stong winds
(Canvas) 5m Bell tent - heavy weight canvas & dutch lacing includes huge wooden pole for the centre
(Canvas) 6 berth frame tent my parents used to take on family camping trips in the 80s and we used at last years British GP - which was its first outing in about 28 years
(nylon) Vango Tornado 300 - mostly used in the depths of winter camping
(nylon) Wynster Curlew 5 - good tent, stands up to bad weather well - liked this tent so much that when the original tent started to show its age after a couple of seasons of heavy use we bought another.
(nylon) Royal Normandy 5 - huge 5 berth tunnel tent we've had for about 10 years, very beaten up now, doesnt get many outing now.
(nylon) Vango Sigma 300 - bought as a stop gap
The benefits of canvas are that they are cooler in the hot sun - when at Bloodstock last year when everyone else was getting baked out of their tents we were still quite cool inside. Equally they are warmer at night as the canvas doesnt lose heat as quickly - so we can keep the Eldorado plesently warm using a tilly lamp or 2
They dont rustle like a crisp packet in the wind and quieter in the rain.
To us - if a tent is put away damp at the end of a trip then it needs drying out - doesnt matter if it is canvas or nylon - both will get mildew if they are stored when they are put away damp. So theres pretty much always a tent hanging on the stair bannister drying.
We have found with our use of tents with camping most weekend of the year for Motorsport evets we'll get a couple of seasons out of a nylon tent, while a canvas tent will fade a bit but will keep going - the canvas poles tend to be more hardwearing - all our nylon tents (except the Tornado with alloy poles) suffer from the fibre glass poles fatiging and snapping - so often have to bodge a repair then replace the broken pole at home later