Please don't drill this rifle
Mike,
Congrats on getting this rifle at such a good price! It believe it is worth much more than what you paid. But let me join the chorus of others here asking you to please not drill into it. It is not a matter of losing value (which is a certainty, but you don't have a lot of money in it). It is more a matter of wrecking something that has some historical value.
Consider:
1) It is an original Lee-Speed sporter in nice shape, which is uncommon to start with.
2) It is a No.1 Pattern, the highest grade offered, making it even more rare, and was originally expensive for someone on a middle class income.
3) Rarer still, it is from a known (and interesting) maker, F. Beesley. A minority of Lee Speeds are marked with a maker's name. Knowing the gunmaker adds to the story of this particular rifle.
4) It is inscribed to a known owner, even more rare, and very interesting.
5) It has a date! Very few Lee Speeds can be pinned down to a known date. Do know how many such rifles I have struggled to find dates for, based on markings, anecdotes, and crumbling ledgers? And yet here is yours plain as day.
6) Furthermore, the date is pre-1899, which for U.S. collectors is highly prized, because those are categorized as antiques and not treated as firearms by Federal law, allowing them to be transferred and shipped to any law-abiding recipient anywhere in the U.S. (with some exceptions, consult your lawyer!) The value increases greatly should you ever decide to sell to an American collector. Furthermore, pre-1899 Lee Speeds are far less common that post-1899 examples.
7) There is really no need to chop up this well-preserved and interesting rifle. There are so many other Lee Enfields out there that you can scope more easily and without any hesitation about wrecking an historical piece. A No4 Mk1* would be perfect. If you were in the U.S., I would trade you one instantly that is already scoped, and throw in the money for what you paid for this one, plus some. I'm sure others would do the same.
8) Rifles of this era, as others here have wisely observed, were not intended to be fitted with scopes. It's true that a few years later (into the Edwardian era) I have seen a few scoped examples of Lee sporting rifles, but these mounts appear to have been added later (the scopes themselves being of 1920s vintage), and they were not always well done. Some of the high-end gunmakers could add the scope, but to duplicate that today in a period-correct way would be expensive, and as noted above, "easy to get wrong." An ex-military SMLE or a later No.4 could be done much more easily, and would be reversible if it didn't work out.
It is yours, of course, to do with as you wish, but this is my recommendation. Please consider leaving this one in its original state and enjoying it as such, or selling it to another collector and acquiring a rifle more suitable for a scope. You got a great deal on this, but there will be another one out there that is better suited to your goals.
Whatever you decide, it would be very valuable to my project if you could share some data on the rifle, especially the markings. I have a full survey I can send you, but just some representative photos would probably suffice, or just a list of markings. This allows me to compare it to other rifles of similar configuration and vintage. I am especially interested in where the "serial number" mentioned in the catalog is found on the rifle, and if there is a number on the action below the bolt handle, and anything on the barrel.
Best regards,
JC5