There's a brilliant tool called the Knightston diversion plotter, basically a little plastic disk that works like a mini flight computer and very easy to use in flight. It will give you very accurate headings to fly and accurate 6 minute markings along the chart. Sadly they're very difficult to come across. If you'd like on send me a PM and I'll disclose the location of where they come from (from memory somewhere like coventry!
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