Any update on this? I'd definitely be very interested - been to the Conkers Parkrun before.
Elvaston Castle has excellent potential and doesn't get too busy - close to the A50 and A52 too. A loop from the car park round the grounds is almost bang on 5K. Only issue would be other users (dog walkers, cyclist, horseriders). Alvaston Park might work too if it goes down by the river. It has a car park and cafe also but busy on a Saturday morning with football and BMX. I live next to Allestree Park and would agree it is too small plus the A6 is a busy road which would need crossing to get the distance. Small car park and no cafe. Darley Abbey might work but it's extremely busy (even this morning) on a Saturday morning with dog walkers, BMF and Derby Rowing Club.