[Option strike prices on IG API]

I have resolved this by looking for an option that's deep in the money at the expiry time. At expiry, the option's value is equal to the market price minus the strike price, so I can work out the strike price from there. I can then work out the strike price for other options if the markets not too volatile as it moves by 10 points between epics except at the extremes.

It's really not pretty but it's the best I can do at the moment. If anyone comes up with a better solution then please let me know.  

[Looking at charts from the last few days in different time frames]

I'm not aware of a way to prevent it resetting back to the current time but there is a date picker you can use to prevent having to scroll. It's on the chart menu, third from the left, next to Mid/Bid/Ask. You need to scroll over to see it.

[IG Option data from API]

Yes, it's all there in the same way as any other market. If you use the marketnavigation endpoint, you can find the hierarchy ids and epic names. For example, "DO.D.CABLE.50.IP" is currently Daily GBPUSD 12410 CALL.

[Option strike prices on IG API]

Daily FX options on the API seem to have epic names like "DO.D.CABLE.35.IP" where the number varies between 1 and 100. Different numbers represent different strike prices and alternate between calls and puts. For example

100: Daily GBPUSD 12140 CALL
99: Daily GBPUSD 12140 PUT
98: Daily GBPUSD 12160 CALL
97:Daily GBPUSD 12160 PUT
.
.
.
2: Daily GBPUSD 12800 CALL
1: Daily GBPUSD 12800 PUT

I think these strike prices are different on different days. Presumably they change as the spot price moves, otherwise they would drift deep out of the money over time.

I want to make use of historical option data, downloaded using the prices endpoint. My problem is I can't find what the strike price was for e.g. DO.D.CABLE.35.IP on10th April. Does anyone know how to get or work out historical strike prices for these option epics?

Thanks!