Hello Sonishekhar, welcome to Stamp Community.

The stamps are from Great Britain, the first country to have a postage stamp and thus the only country to be allowed to have No country name on their stamps.
The King shown is Hing George V (5th) (KGV).
The first stamp is ripped in a corner, bent in another, gouged away along the bottom. This is only without examing teh back for damage or watermark. Thus probably worth nothing in this condition. Cjeck for watermarks differences though and re-entries perhaps caused by re-engraving mistakes (scan at a high resolution).
Normally worth about 1 GBP, depending on condition and colour and heavy or light cancellation / postmark.
On all of the 1d stamps from 1912-24 the chance exists to have a reversed or inverted Q instead of an O in the ONE PENNY. These are worth hundreds of pounds.
The watermark can be reversed or onverted or reversed and inverted. Quite a study to look at these. use watermark fluid or lighter fuid carefully under well-ventilated conditions.
The next looks OK, so check the back, soak in clean water to remove the dirt accumulated over the many years, look for watermark also.
Stanley gibbons numbers are between 357-361 or 419 (1924-26) depending on colour.
The overpint looks to be from use in Northern Ireland I think, I do not know the number or value.
The 3d (pennies) (d= roman for denarius = silver penny) is numbered betwen 374 and 377 or 423, some shade of violet, valued at around 2 GBP. The watermark will determine a more costly stamp also with this one.
edit: all numbering is subject to verification by the more experienced and well versed gents previously spoken above.