According to CME Daily Bulletin for GBP calls and puts, on 20180327 the maximum open interest for calls has been registered at 1425 and reached 379. Change in open interest was +262. Given the current forward points value 49.95, FOREX target price would be 1.42001. Maximum open interest for puts has been at 1410 and has made 257. The FOREX target price is 1.40503.
See how to use Daily Option Expiry Levels at http://zentrade.online/use-daily-option-expiry-levels/.
Alternatively, find below distribution according to combined maximum volume and open interest.