I can remember using Rebecca every day over 8/8 out of Rissy while trainee instructors pattered on. We used true bearings plus the odd Rebecca position line to stop bouncing off airways. Apart from Rissy, a quick 'strobe' of the Shawb Eureka station kept you in the right area. I can remember getting readings of 20-30nm. If you had a good idea of the winds aloft and kept an eye on Blogg's heading changes & speed, one's DR became pretty sharp. Did Pershore have a Eureka/Rebecca? There must have been another one somewhere. Although the bearing needle under the range indicator flopped about, I can never remember using it for a letdown although we discussed the theory in the event of radio failure. The combination of true bearings & Rebecca range readings for 50 minutes allowed one to position to the northwest of LR at about the right slot time to get a radar pick-up. This was early 70's.